Question

Please help!!
Simplify the expression by using a double angle formula cos^2(40) - sin^2(40)

Answer 1

this can be written as cos(80)

Answer 2

did u get it @ariabstr

Answer 3

I dont know how to answer it now

Answer 4

would it be \[\sin \frac{ \pi }{ 18 } - \cos \frac{ \pi }{ 18 }\]

Answer 5

@KissMyAxe

Answer 6

cos^2 x-sin^2 x=cos 2x

Answer 7

@Er.Mohd.AMIR has explained it!

Answer 8

its formula