Question

Trigonometry problem

Answer 1

Hi! So, I'm pretty sure the answer is 1 (rounded).

However, I'm not sure if you're trying to find the answer to COS pi/10 or "the function in terms of cofunction of a complementary angle" which I'm not too sure about. I've given you the answer to the first part if this was not the right way to read the problem I deeply apologize.

Explanation:

Using any calculator with the Cos, Sin, and Tan function, you can input

COS (pi / 10) which equals .9999849678 (which you can round as needed)

Answer 2

The complement of cosine is sine. Cos (A) = sin(pi/2 - A)

So cos(pi/10) = sin(pi/2 - pi/10) = sin (5pi/10 - pi/10) = sin (4pi/10) = sin(2pi/5)

Hope this helps!