







A trough with a triangular cross section 
20160521 

From Clarice: A trough having an equilateral triangle end sections has sides equal to 0.4 m and 7m long.what is the volume of the liquid in the container if the depth of the water is one half the depth of the trough? Answered by Penny Nom. 





Sloping my yard away from my house 
20160415 

From Harold: I need to slope a area of my yard away from my house and garage. The length of my house is 80 feet long and i need to slope it 22 feet away. I want to raise the dirt at the foundation by 6 inches and slope it down to nothing at the width of 22 feet. How much soil would i require? Answered by Penny Nom. 





A triangular shaped garden 
20160113 

From Demetrie: Dwayne's garden is triangleshaped with two equal sides and a third side that is 4 ft more than the length of an equal side. If the perimeter is 49 ft, how long is the longest side? Answered by Penny Nom. 





The perimeter of a triangular plot of land 
20160111 

From Janelle: I need to fence off 6.5 acres. The plot is triangular shape. How many feet would I be fencing off? Answered by Penny Nom. 





The surface area of a triangular prism 
20150603 

From Alex: Find the surface area of a triangular prism with Isoceles triangles and dimensions 4 feet by 6 feet Answered by Penny Nom. 





A tennis ball in a triangular prism 
20141006 

From Anna: Hi, I need to find the the base and the height of a triangular prism, but I only know the diameter of a tennis ball that fits exactly in the triangular container.. The diameter for the ball is 8.50cm.
Can you help me find the formula?
Thank you! Answered by Penny Nom. 





A barge of triangular cross section 
20140818 

From tushar: a barge of triangular cross section is 20m long 12 m wide and 6m deep.its floats in SW at a draft if 4m find its displacement Answered by Penny Nom. 





A gravel pile in the shape of a triangular pyramid 
20130404 

From Casey: Hello
Right now I am stuck and I feel embarrassed because I feel like the answer is so easy I should know it.
I am working on a project and need to find a volume of gravel it will take to occupy this triangular prism like area. I am not sure what formulas I should use whether it be that for the volume of a pyramid or something more complex? Basically it forms a right triangle at one side then from there all points slope to one singular point about 10412mm away.
I am attaching a picture drawn up in paint with the actual dimensions to clear up any confusion.
Thank you for any help.
Casey Answered by Penny Nom. 





Question 
20130404 

From Casey: Hello
Right now I am stuck and I feel embarrassed because I feel like the answer is so easy I should know it.
I am working on a project and need to find a volume of gravel it will take to occupy this triangular prism like area. I am not sure what formulas I should use whether it be that for the volume of a pyramid or something more complex? Basically it forms a right triangle at one side then from there all points slope to one singular point about 10412mm away.
I am attaching a picture drawn up in paint with the actual dimensions to clear up any confusion.
Thank you for any help.
Casey Answered by Penny Nom. 





A railroad embankment 
20130122 

From clint: the pennsylvania railroad found it necessary,owing to land slides upon the roadbed,to reduce the angle of inclination of one bank of certain railway cut near pittsburgh,pa.,from an original angle of 45 degrees to a new angle of 30 degrees. the bank as it originally stood was 200 ft.long and had a slant length of 60 ft.. find the amount of the earth removed, if the top level of the bank remained unchanged. Answered by Penny Nom. 





The volume of a wedge 
20120528 

From olwethu: volume of wedge that have side 3,3 cm and 6,2 cm and 20 cm long? Answered by Penny Nom. 





Triangular numbers that are square 
20111227 

From Luke: The “TnS” is a positive integer which is both Triangular number
and Square number. For example, 36 is a “TnS” number
since 36=1+2+3+4+5+6+7+8 (Triangular number)
and 36=6x6 (Square number).
What is the next “TnS” which is greater than 36? Answered by Penny Nom. 





The volume of a triangular shaped aquarium 
20110507 

From Jeff: HI, I searched the site but really couldn't find my answer,
at least that I could understand! I have a triangular shaped aquarium
( think of a cube, except its an equal triangle shape). all 3 sides are 48 inches,
and it is 34" tall. Can you please tell me what the volume is in gallons?
Thanks! Answered by Penny Nom. 





The volume of a triangular pyramid 
20110415 

From Chelsea: There is a triangular pyramid which is an equilateral on the base with all sides 16.5 and the height is 25. I have to find the volume. Please help! Answered by Penny Nom. 





Pyramids and parallelograms 
20100401 

From Vivi: Hi, my name is Vivi, and math teacher is giving a geometry test. I tend to forget how to find the surface area and volume of triangular pyramids and parallelograms. Do you have a way of remembering how to find the surface area? Answered by Harley Weston. 





A champagne pyramid 
20100322 

From Kathy: I have 680 champagne glasses and my pyramid can only be 15 levels high. How many glasses need to be on each level? Is there a formula I can use? Answered by Robert Dawson. 





A triangular prism 
20100113 

From Breon: what is the formula for a triangular prism? Answered by Robert Dawson. 





A triangular pyramid 
20100105 

From ally: how many vertices, edges, faces in a triangular pyramid? Answered by Robert Dawson. 





A triangular shaped ditch 
20091112 

From Tim: I am planning on constructing a triangular shaped ditch the measures 550 meters in length, 6 meters wide at the surface, .3048 meters at the invert of the ditch and 2 meters deep.
How many cubic meters of material will have to be excavated to construct
this ditch Answered by Robert Dawson. 





Triangular Numbers 
20090616 

From Chinonyerem: Question from Chinonyerem, a student:
Each of the numbers
1 = 1, 3 = 1+2, 6 = 1+2+3, 10 = 1+2+3+4 ,...
represents the number of dots that can be arranged evenly in an equilateral
triangle:
.
. . .
. . . . . ...
. . . . . . . . . .
This led the ancient Greeks to call a number TRIANGULAR if it is the
sum of consecutive integers, beginning with 1. Prove the following facts
concerning triangular numbers:
(a) A number is triangular if and only if it is of the form n(n+1)/2 for some n >= 1
(b) The integer n is a triangular number if and only if 8n+1 is a perfect square
(c) The sum of any two consecutive triangular numbers is a perfect square
(d) If n is a triangular number, then so are 9n+1, 25n+3, and 49n+6 Answered by Penny Nom. 





A triangular pyramid 
20090226 

From Craig: Can you help with this question:
Write the names of the faces and the number of each kind of face on a triangular
pyramid? Answered by Penny Nom. 





Solid figures 
20090210 

From Rebecca: I need to know the names of solid figures. I have several pictures that I need to answer what type they are.
Thanks, Rebecca 3rd grade Answered by Penny Nom. 





A triangular pyramid 
20090206 

From kamran: what would be an example of a triangular pyramid Answered by Stephen La Rocque. 





Faces, edges and vertices 
20090204 

From sheila: what is the relationship between the number of faces and the number of edges of a triangular pyramid ? Answered by Penny Nom. 





The volume of a prism 
20090119 

From Mady: What is the general equation used to find the volume of a triangular prism? Answered by Robert Dawson and Harley Weston. 





Triangular prisms and pyramids 
20090110 

From KJ: What are some items found in a home or school that could be considered a triangular prism or triangular pyramid? Answered by Robert Dawson and Penny Nom. 





A triangular field 
20080815 

From joneka: Barb walked five times aroun a triangle field all together she walked 435 feet the first side of the triangle fiel is 23 feet the length of the other two sides are of the same measure. What are the dimensions of the triangle field? Answered by Penny Nom. 





Triangular prisms and pyramids 
20080303 

From LORENA: hi i am in yr 6 and i need to know how many faces,vertices and edges these shapes have..
. TRIANGULAR PYRAMID
. TRIANGULAR PRISM Answered by Penny Nom. 





A square and an equilateral triangle 
20080210 

From Emily: A square pen and a pen shaped like an equilateral triangle have equal perimeters. Find the length of the sides of each pen if the sides of the triangular pen are fifteen less than twice a side of the square pen. Answered by Stephen La Rocque. 





A triangular lot 
20071017 

From Brian: Seeking the square footage of a triangular property lot, dimensions are: 620 X 620X 720. Answered by Penny Nom and Melanie Tyrer. 





A triangular trough 
20070719 

From janine: A trough is formed by nailing together, edge to edge, two boards 11 ft. in length, so that the right section is a right triangle. If a 15 gallon of water are poured into the trough and if the trough is held level so that a right section of water is an isosceles right triangle, how deep is the water? (231cu.in=1 gal.) Answered by Penny Nom. 





The area of a triangular pyramid 
20070718 

From Jhezelle: What is the formula of finding the surface area of a triangular pyramid? Answered by Penny Nom. 





The number of blocks on the face of a pyramid 
20070627 

From Heather: I was wondering if there was an equation in order to calculate the number of blocks on the face of a pyramid.
For example:
X
X X
X X X
Is there a specific formula in order to calculate that there are
6 blocks here?
Thank You,
Heather Answered by Harley Weston. 





The volume of a triangular prism 
20070601 

From Hannah: How do I find the area of the base of a triangular prism, so that I can find the volume by using the equation on the attachment. The formula is that volume equals one half times (base times height) times triangle height. Thank you for your help.
Hannah Answered by Penny Nom. 





A triangular prism 
20070326 

From Tom: Hi, I need to find a container in the shape of a triangular prism that will fit
four table tennis balls (this is for a math project!). These balls have a
diameter of 4cm, so a radius of 2. I know that the formula for finding
an incircle from a triangle is: radius of incircle =
2area of triangle / perimeter of triangle
But I need to know the length of one side of the triangle from the incircle
(the triangle needs to be equalateral).
Can you help me find a formula for this?
Thanks so much!
Tom Answered by Penny Nom. 





Surface area of a triangular prism 
20070221 

From Katrina: What is the formula to finding the surface area of a triangular prism? Answered by Gabriel Potter. 





a specific 3d shape 
20070212 

From Robby: What three dimensional shape has 6 vertices, 5 faces, and two congruent triangular bases? I can't find the answer to this question anywhere. Your help will be appreciated. Thanks, Robby Craig Answered by Pam Fowler, Gabe Potter and Walter Whiteley. 





Water in a triangular trough 
20070130 

From Trina: the trough is 5 feet long and its vertical cross sections are inverted isosceles triangles with base 2 feet and height 3 feet. water is draining out of the trough at a rate of 2 cubic feet per minute. at any time t, let h be the depth and v be the volume of water in the trough. a. find the volume of water in the trough when it is full b. what is the rate of change in h at the instant when the trough is .25 full by volume? c. what is the rate of change in the area of the surface of the water at the instant when the trough is .25 full by volume? Answered by Penny Nom. 





1, 3, 6, 10... 
20061215 

From Lisa: What is the nth term for the sequence, '1, 3, 6, 10...' and could you say how you got the anwser. Answered by Stephen La Rocque and Penny Nom. 





The surface area of a triangular prism? 
20061029 

From Amanda: What is the formula for the surface area of a triangular prism? Answered by Haley Ess. 





The volume of a triangular box 
20060912 

From Irene: How do I find the volume of a triangular box? Answered by Penny Nom. 





A triangle of 50p pieces 
20060222 

From Stuart:
Ok, so i am collecting 50p pieces and arranging them on my desk in the shape of a triangle.
eg
50p
50p 50p
50p 50p 50p
50p 50p 50p 50p
I want to work out how much money I'm saving just by knowing how many rows of coins there are. If i can work out how many coins there are just by knowing how many rows I have I can just divide by 2 to find out the amount in dollars.
Answered by Penny Nom. 





Shapes 
20051112 

From Tonya and Hailey: MY THIRD GRADERS TEACHER HAS SENT HOME HOMEWORK ASKING FOR THEM TO FIND REALWORLD OBJECT IN MANY DIFFERENTS SHAPES A FEW HAVE US STUMPED Answered by Penny Nom. 





A triangular pyramid 
20051022 

From Stacee: When stacking oranges to form a triangular pyramid, each orange touching 3 oranges below it. In order to have a pyramid with 6 layers, how many oranges should be on the bottom layer? Answered by Penny Nom. 





A triangular lot 
20050521 

From Linda: I am looking to purchase a piece of property, and I need some help trying
to figure out the square footage of the land. I know that
normally if I multiply the length and width I could get my answer. However,
this piece of land is an odd shape and has 3 measurements. Can you
please help me.
The measurements for this piece of land is:
97.8'
201.2'
139.7' Answered by Penny Nom. 





A triangular prism 
20021030 

From Daniel: I was wondering what a triangular prism was. Answered by Diane Hanson. 





A triangular prism 
20020428 

From A student: Need the formula for the surface area of a triangular prisim? Answered by Penny Nom. 





Triangular numbers 
20020426 

From Anika: Can you please tell me what a triangular number is? Answered by Penny Nom. 





A triangular pyramid 
20010514 

From Kumar: In a Pyramid OABC, all the three sides of the base: a, b, c are known. Also known are the angles between the three sides from the vertex O: Angles AOB, BOC, COA. With this information, is it possible to calculate the lengths of the three sides: OA, OB & OC. Answered by Chris Fisher. 





Volume and surface area of a cylinder and a triangular prism 
20010331 

From Kevin: I was wondering how do you find the volume and surface area of a cylinder and a triangular prism. Answered by Penny Nom. 





Triangular numbers and square numbers 
20000302 

From Emily McCallum: Would someone find me some math activities using triangular numbers and square number. Especially acitivities that actually form the shapes. They need to be at the 5th grade or 6th grade level. But you can not find anything that can be tauht at these level, that fine. I just need to be able to teach this new subject or kind of math to my kids. Answered by Rick Seaman and Penny Nom. 





Pyramids and prisms 
20000118 

From Tyler: What's the definition of a Triangular Prism and a Triangular pyramid. Answered by Penny Nom. 





Cannonballs 
19990127 

From Roger King: How many cannonballs can be stacked in a triangular pyramid? Answered by Penny Nom. 





Triangular Numbers 
19981030 

From Matt: i would like to know about triangular numbers and it history i would also like to know about the history of prime numbers thank you Answered by Chris Fisher. 





Triangular Numbers. 
19970908 

From Rachel: Show visually that the square number 16 is the sum of two triangular numbers. Which two? Answered by Penny Nom. 

