







The circumcentre, centroid and orthocentre of a triangle 
20120424 

From Nazrul: The circumcentre, centroid and orthocentre of a triangle is
given. The distance between circumcentre and orthocentre is also
given.
How can I draw the circle?
Please Help me. Answered by Chris Fisher. 





The centroid and circumcircle of a triangle 
20081209 

From prateet: in an equilateral triangle prove that the centroid and centre of the circumcircle coincide
here i am not clear about the concept of centroid and circumcircle
i cant understand how AGis 2/3 AD.
please help in details about the topic mentioned. Answered by Harley Weston. 





The centroid of a polygon 
20071229 

From David: I am playing around with an idea. I've read previous answers to questions
(using surveyor calculation methods) related to finding the area of an irregular
shape parcel of land (or irregular polygon). Is there a formula or method for
calculating the centroid (midpoint) for this type of polygon. I've seen plenty
of methods for calculating the midpoint for a triangle or regular shape poloygon
but few for an irregular shape polygon such as a parcel of land. Thanks... Answered by Harley Weston. 





Find the centroid 
20071126 

From josh: vertices X(2,6) Y(4,10) Z(14,6) find the coordinates of the centroid Answered by Stephen La Rocque. 





The centroid of a triangle 
20060118 

From Andrea: I am trying to find the centriod of a triangle. I have been given the three vertices of the triangle: A (25, 20), B (5, 40), and C (15, 30). I believe I calculated the correct midpoints: AB(E) (5, 5), BC(D) (5, 5), and AC(F) (15, 30). When I graphed these points I came up with the solution (5, 10), but I can't seem to write the answer out (equations of the lines, etc) correctly. Any help would be greatly appreciated! Answered by Penny Nom. 





The centroid of a triangle 
20050407 

From Maria: Q3)find the coordinates of the centroid of triangle ABC
i want your help here to solve the 3rd question i got stuck. Answered by Penny Nom. 





Vectors in three space 
20041030 

From Jo: I have two questions that I just cannot visulise and dont know how to get started on them..!
1. Ship X is sailing North at 4m/s and Ship Y is sailing due East at 3m/s. A sailor on Ship X climbs a vertical pole at 1/2 m/s. What is the velocity of the sailor on Ship X relative to an observer on Ship Y? State it's magnitude and direction.
Not sure where to start with this one...
2. Show, using vectors, that for any tetrahedron, the segments joining the midpoints of the opposite edges are concurrent.
i know what a tetradedron is, and what I am proving but do I solve simultaneously for a specific case?? Answered by Walter Whiteley. 





The point where all the medians meet 
20040225 

From A student: What's the name of the point where all the medians meet? Answered by Penny Nom. 





A centroid problem 
20000602 

From Kerstin: An isoceles triangle has sides measuring 13 cm, 13 cm, and 10 cm. Find the distance from the centroid to the vertex of a base angle. Answered by Harley Weston. 





Two sides and a bisectrix. 
19981111 

From Victor Grinshtein: I am looking for someone who can tell me how to construct a triangle by 2 sides and a bisectrix using a compass and a ruler. Answered by Chris Fisher. 





Volumes 
19980829 

From Lorraine Wall: Consider the region in the first quadrant bounded by the x and y axes, the vertical line x=3 and the curve y = 1 / (x squared + 3). Determine the volume of the solid by rotating this region about the xaxis. Now that is the first part. I then have to find the coordinates of the centroid of the solid by rotating this region about the xaxis. Thanks. Lorraine Answered by Harley Weston. 

