Question

simplify cos^4x - sin^4x

Answer 1

cos^4x - sin^4x = (cos ^2 x + sin ^2 x) * (cos ^2 x - sin ^2 x).

What does (cos ^2 x + sin ^2 x) equal? Hint: It is one of the identities.

Answer 2

?

Answer 3

what is it???

Answer 4

Do you know trid identities?
How much do you know?

Answer 5

im learning identities now. Dont know what trid means.. Its year 10 extension maths. I only know basic trig..

Answer 6

Sorry i meant trig... so what basic trig formulas do you know?

Answer 7

sin cos tan

Answer 8

So you havent done sin2x and cos2x yet?

Answer 9

Look at the attached Pythagorean Identies:

http://www.sosmath.com/trig/Trig5/trig5/trig5.html

Answer 10

cos^4x - sin^4x = (cos ^2 x + sin ^2 x) * (cos ^2 x - sin ^2 x)

= ONE times (cos ^2 x - sin ^2 x)

Answer 11

oh ok so i just need to remembe these identities... thx