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trig identities

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11 items are filed under this topic.
A trig identity 2012-01-08
From Joe:
Prove this Trig. Identity :

((cos2θ + sinθ-1) / tanθ ) + sin2θ = cosθ

Answered by Penny Nom.
A trig identity 2010-01-05
From Christine:
I need help with this whole paper here is one problem

by the ^2 i mean squared pleease

Answered by Penny Nom.
Trig identities 2009-01-05
From Michael:
1) Determine if the following is an identity. If it is, prove it, If it isn't state it.

tan x + cot x = sec x * csc x


1 - (cos^2) x = 1+ (cot^2) x

Answered by Robert Dawson and Harley Weston.
Trig identities 2007-07-30
From Suzanne:
I'm a UR University Graduate (with High honours!) but not in math: I'm taking GeoTrig, Sk Learning version, and the text is poorly written. But I was flying through the material until I hit the Trig Identities. I just don't get WHY we have them, why we should know them? What good is this "theory". All that "simplying" rarely yeilds a simple-er version! Also, give me advice for how to study them. Thanks Suzanne
Answered by Harley Weston.
Two trig questions 2006-04-04
From mandy:
I have a few questions that I need help with for my precal class in college. The following have to prove the trigonometric identities:

cos4x + 2cos2x sin2x + sin4x = 1

sin4x - cos4x = 1 - 2cos2x

thanks you,

Answered by Stephen La Rocque.
cos(3X) 2006-03-29
From Joshua:
I'm having trouble proving that cos(3X)=cos3X -(cosX)(sin2 X)
Answered by Penny Nom.
Some trig expressions 2004-05-23
From A student:

sin A + sin B = 2sin(A+B/2)cos(A-B/2)

cos A - cos B = -2sin(A+B/2)sin(A-B/2)

cos A + cos B = 2cos(A+B/2)cos(A-B/2)

sin A - sin B = 2cos(A+B/2)sin(A+B/2)

Answered by Penny Nom.
An identity in trigonometry 2002-10-17
From Alex:
I really need help with proving this identity. (1+cosx+sinx)/(1+cosx-sinx) = secx + tanx
Answered by Penny Nom.
Proving a trigonometric identitiy 1999-12-17
From Ryan:
I need to figure out how to prove that sec2x + csc2x = sec2x csc2x. 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 1999-06-03
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.

Trig identities 1995-11-30
From Azmat:
Why do we work on the two sides of a trig identity separately?
Answered by Harley Weston.



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