Find cos2x if sin(X)= 9/41.

Question

Can you please show every step? Thanks!

Answer 1

Hi Imani,

 

Do you know the three identities for the cosine of twice an angle? If not, take time to locate them in your trig book.

 

One of them is cos2x = 1-2sin²x. Since you are given sinx = 9/41, substitute that value into the aforementioned identity and simplify.