Question

I need help (AGAIN) lol
Which of the following are identities? there can be more than 1 correct answers...
A) cos^2 3x-sin^2 3x=cos6x
B) (sinx+cosx)^2=1+sin2x
C) sinx+sin5x=tan3x
D) sin^6 x+cos^6 x=4-3sin^2 x

Answer 1

You need to use your other identities (here is a table of them.. http://www.sosmath.com/trig/Trig5/trig5/trig5.html ) and work through each answer to find which one equals the others. Trig identities are just big puzzles; once you move the right it all works out.

Answer 2

alright. thank you

Answer 3

\[\cos^2 a - \sin^2 a = \cos (2a)\]

Answer 4

(sinx+cosx)^2=sin^2x+2sinxcosx+cos^2x=1+sin2x

Answer 5

idk what the last two mean

Answer 6

mean nothing

Answer 7

so you are saying the first two are correct?

Answer 8

yep

Answer 9

basically yeah

Answer 10

nice. thank you