







A trig identity 
20151028 

From Gail: verify sec(x) =cot(x)+tan(x)/csc(x), the csc(x) is under both the whole term cot(x) + tan(x) Answered by Penny Nom. 





A trig identity 
20130104 

From Tehmas: Prove sinC+sinD=2sin(C+D/2)cos(CD/2) Answered by Harley Weston. 





A trig identity 
20120108 

From Joe: Prove this Trig. Identity :
((cos2θ + sinθ1) / tanθ ) + sin2θ = cosθ Answered by Penny Nom. 





I started with Euler's identity and manipulated it 
20111114 

From anonymous: I started with Euler's identity and manipulated it
e^i*pi=1
e^i*pi=(1)^1
e^i*pi=1
e^i*i*pi=(1)^i
e^pi=(1)^i
e^pi=(1)^i
type it in in a calculator and you get e^pi=23.1406926... and
(1)^i=0.0432139183... What did I do wrong? Answered by Robert Dawson. 





sin A/1+cos A + 1+cos A/sin A = 2cosec A 
20111020 

From Neeraj: sin A/1+cos A + 1+cos A/sin A = 2cosec A Answered by Penny Nom. 





Tan(x+pi)tan(pix)=2tan(x). 
20110109 

From Steven: Verify the identity:
Tan(x+pi)tan(pix)=2tan(x) Answered by Penny Nom. 





A trig identity 
20100327 

From Anne: Prove:
(2tanxsin2x)/2sin^2x=tanx Answered by Penny Nom. 





A trig identity 
20100308 

From Kim: I am having trouble proving this trig identity
(sin^2 x + 2 cos x1) / 2+cos x  cos^2 x = 1/ (1+ sec x) Answered by Penny Nom. 





A trig identity 
20100124 

From Natalie: hi, i need help proving the following trig identity. i cant seem to figure out how to do it.
thanks so much.
(1+sin2x)/cos2x = cos2x/(1sin2x) Answered by Penny Nom. 





A trig identity 
20100121 

From Alesia: How to prove Csc(A+B) = (csc A Csc B)/ (Cot A+ Cot B) Answered by Penny Nom. 





A trig identity 
20100105 

From Christine: I need help with this whole paper here is one problem
csc^2xcot^2x/1sin^2x=sec^2x
by the ^2 i mean squared pleease Answered by Penny Nom. 





sin x / 1+ cos x = csc x  cot x 
20091118 

From Mansi: i need a hint on how i could prove the following identity:
sin x / 1+ cos x = csc x  cot x Answered by Harley Weston. 





A trig identity 
20090710 

From sam: I need to prove:
tan x (cot x + tan x) = sec2 x
(the "sec2" is "sec squared")
I am totally stuck!!
Thanks! Answered by Stephen La Rocque and Harley Weston. 





A trig identity 
20090630 

From sumayya: prove that sin A (1+tan A)+cos A (1+cot A)= sec A+ cosec A Answered by Robert Dawson. 





Finding an Acute Angle using Trigonometric Identities 
20090629 

From Nazrul: How can I find the value of A if sinAcosA=1 , where A is an acute angle. Answered by Stephen La Rocque. 





sin x/ 1+cos x = 1cos x/ sin x 
20090530 

From rita: prove: sin x/ 1+cos x = 1cos x/ sin x Answered by Stephen La Rocque. 





Sec(2x) 
20081123 

From Evan: Prove that this is an identity...
sec2x = sec^2x / 2  sec^2x Answered by Harley Weston. 





A trig Identity 
20081113 

From Rebecca: Question from Rebecca, a student:
How do I prove:
1/sin@ csc@ 2sin@
________ + ______ = _____
1 + CSC@ 11/sin@ cos^@ Answered by Penny Nom. 





A trig identity 
20081103 

From Student: verify cos(2x)=(cot(x)tan(x))/(cot(x)+tan(x)) Answered by Penny Nom. 





TRIG IDENTITIES 
20080817 

From VINCE: HOW DO YOU SIMPLIFY THE FOLLOWING:
2sin3(theta)cos3(theta)?
Regards Answered by Harley Weston. 





Graphing Using Double Angle Identities 
20080716 

From Hodan: the Question is:
Describe how you could use your knowledge of Double angle formulas to sketch the graph of each function. Include a sketch with your description.A) F(x)=sin x cos x
B)F(x)=2 cos(squared)x
C) F(x)= tan(x) (divided) by 1tan(squared) x Answered by Janice Cotcher. 





cos3A=1/3 find cos6A 
20080515 

From mike: cos3A=1/3 find cos6A Answered by Penny Nom. 





2 tan theta /(1 + tan^2 theta) = sin 2theta 
20080325 

From Charmaine: I'm having trouble on where to begin proving identities. I must prove that
(2 tan theta / 1 + tan^2 theta) = sin 2theta Answered by Penny Nom. 





(1tanx) / (1+tanx) = (1sin2x) / cos2x 
20080214 

From isaiah: i'm having trouble proving 1tanx / 1+tanx = 1sin2x / cos2x, can anyone help me from going crazy? Answered by Penny Nom. 





A trig identity 
20071128 

From Julia: sin4x 1  cos2x
 x  = tanx
1  cos4x cos2x Answered by Harley Weston. 





A trig identity 
20071110 

From James: I need to prove trig identities, and I can't figure this one out
1 + sinx  cosx 1  cosx
 = 
1 + sinx + cosx sinx
Answered by Chris Fisher. 





A trig identity 
20061228 

From Courteny: Prove that 1  cos 2x + sin 2x (divided by) 1 + cos 2x + sin 2x = tan x Answered by Penny Nom. 





A trig identity 
20061214 

From Zamira: i need help with this proof: ((cot(x)tan(x))/ cot(x) + tan(x)) = cos (x) Answered by Penny Nom. 





Sin 2x / 1Cos 2x = 2 Csc 2x  Tan x 
20061206 

From Mark: I need to prove the following: Sin 2x / 1Cos 2x = 2 Csc 2x  Tan x Answered by Steve La Rocque. 





tan1/2x + cot1/2x = 2cscx 
20061104 

From Jazmin: Prove tan1/2x + cot1/2x = 2cscx Answered by Penny Nom. 





A trig identity 
20060604 

From Courtney: Show that this equation is an identity:
(sin x + sin 2X)/(cos x  cos 2x) = cot(x/2) Answered by Stephen La Rocque. 





A trig identity 
20060328 

From Iqbal: Could you please prove,
[tan(x)sin(x)]/sin^{3}(x)=sec(x)/[1+cos(x)]
Answered by Stephen La Rocque. 





A trigonometric identity 
20060122 

From Sarfaraz: Prove the following trigonometric identity.
sin^{2}x = tan^{2}x/(1+tan^{2}x) Answered by Penny Nom. 





A pair of trig equations 
20051205 

From Kevin:
I am trying to solve for A and B but haven't been able to find a trig identity that will help me.
1.414 = .5cosA + cosB
.5 = .5sinA  sinB
how do I solve this?
Answered by Penny Nom. 





cos(2x) = sin(3x) 
20050414 

From A student: Show that if x= 18 degrees, then cos2x =sin 3x. HENCE find the exact value of sin 18 degrees, and prove that cos 36  sin 18 =1/2. Answered by Andrei Volodin, Claude Tardif and Penny Nom. 





tan55.tan65.tan75=tan85 
20050330 

From Jesus: My name is Jesus and I´m a secondary student. I´m trying to verify a trigonometric identity but I don´t know how to do it.please help me!!!!!!!!!.
The identity is : tan55º.tan65º.tan75º=tan85º (the sign (.) indicates multiplication)
Answered by Chris Fisher and Penny Nom. 





A trig identity 
20050306 

From Patrick: im trying to verify this
identity:
sin(x)+sin(5x)
 = tan(3x)
cos(x)+cos(5x)
Answered by Chris Fisher. 





A trig identity 
20031112 

From A student: I can't prove this identity. Can you please help me? (1tanx)/(1+tanx)=(1sin2x)/(cos2x) Answered by Penny Nom. 





A trig identity 
20030520 

From Patty: Please help with the following
1/ tanx + cotx = sinxcosx Answered by Penny Nom. 





Three proffs of a trig identity 
20030318 

From Nadene: Prove the identity. cos [x + (ypi/2)] = sin (x+y)
A hint was also provided which is: "Apply cos (alpha + beta) first then within that apply cose (alphabeta)" Answered by Penny Nom. 





A trig identity 
20030222 

From Ron: We have spent hours trying to solve the following identity without success. Can you give us some hints as to how it is done?
1 + tan(x) tan(2x) = tan(2x) cot(x) 1 Answered by Penny Nom. 





The identity property 
20021107 

From Stephanie: I am a student teacher this semester in the third grade. I was looking at our math competencies and saw that we needed to teach the identity property. Is this the same as the distributive property? If not, what is it? Answered by Penny Nom. 





An identity? 
20021027 

From Jenna: I can't prove
1sinQ 1  = tanQ +  1+sinQ cosQ
Answered by Penny Nom. 





An identity(?) 
20020502 

From A student: prove identity sin^{ 2}x/1sinx= secx+1/secx
Answered by Paul Betts. 





A trigonometric identity 
20020322 

From Debby: I am stuck on a problem and wondering if you can help?? It is: Prove the following: sec^{2}(X)+csc^{2}(X) = sec^{2}(X)csc^{2}(X) Answered by Harley Weston. 





A trig identity 
20010727 

From Jeff: prove this identity and show steps tan(x/2+pi/4)=secx+tanx Answered by Harley Weston. 





Trig identity crisis 
20001129 

From Rhiannon: I have tried many times to find the answer to these problems but I can't I am in grade 12  tan(x)=csc2(x)cot2(x)
 cos(x)/csc(x)2sin(x)=tan(x)/1tan(x)
 cos(x)[ tan^{2}(x)11]/cos^{2}(x)+sin^{2}(x)=sec(x)
Answered by Harley Weston. 





A trigonmetric identity 
20000515 

From Caitlin: My name is Caitlin and my question is from 11th grade math and I'm a student my question is I need to solve this identity : cos x csc x  sin x sec x = 2 cot 2x Answered by Paul Betts. 





Matrices Information 
20000502 

From William Avery: I am an OAC student at Governor Simcoe Secondary School in St. Catharines Ontario. Today at school we were handed an independent study project by our Finite teacher. This assignment is based on Matrices, it involves performing some simple matrix calculations, but also involves a written section. This written section asks for the following: . . . Answered by Marley Weston. 





A trig identiry 
20000223 

From Ashlee: I am having problems doing this problem. Can you help? Verify the identity: (1+cot^{2}X)(1cos2X)=2 Answered by Harley Weston. 





A trig identity 
20000217 

From Eric:
Question: How do I solve this problem? sin3x cos3x _____  _____ = 2 sinx cosx Answered by Chris Fisher. 





Proving a trigonometric identitiy 
19991217 

From Ryan: I need to figure out how to prove that sec^{2}x + csc^{2}x = sec^{2}x csc^{2}x. I am not sure where to start out with it and whether I should use reciprocal, quotient, or pythagorean. Answered by Penny Nom. 





A trig problem 
19990603 

From Stu Barnes: cos(theta) / 1+ sin(theta)=sec(theta)tan(theta) I've being having trouble with this one on my correspondance course. Answered by Harley Weston. 





Triminoes 
19980909 

From Roxanne Hale: I am doing an investigation about a game called triminoes (like dominoes). The game is played using triangular pieces of card. Each card has 3 numbers on it. I have to investigate the relationship between the number of trimino cards in a set and the largest number on the cards. I found; largest no. used 0 1 2 3 4 no. of trimino cards 1 4 10 20 35 I was ginen the formula for this which is: UN= UN  1 + 1/2 (n + 1 ) (n+2) UN=no. of trimino cards n= largest no. I don't know how to get to this equation I think it has something to do with triangle numbers! Answered by Penny Nom. 





A trig identity 
19960311 

From Azmat Hussain: Is there an easier/another way to prove the trig identity cos(a+b) = cos(a)cos(b)sin(a)sin(b)? Answered by Penny Nom. 





Trig identities 
19951130 

From Azmat: Why do we work on the two sides of a trig identity separately? Answered by Harley Weston. 

