Question

Given that cos(x)=5/7, what is cos(−x)?

Answer 1

using the identity cos(-x) = cos(x) we can see that cos(-x) = 5/7

Answer 2

Answer: cos (-x) = cos x from complimentary angle properties of sine and cosine functions

Explanation:

Given:

x = 5,

r = 7,

cos (x) = x/r, &

cos (-x) = cos x from complimentary angle properties of sine and cosine functions

Then,

cos(x) = 5/7

cos(-x) = cos(x)

Therefore, cos(-x) = 5/7