Finding the Values of (Theta): Solving cos2theta = 1/4

[ibysaiyan]

Homework Statement

Find the values of (theta),in the interval 0degree$$\leq(theta)$$$$\leq180$$,for which cos2theta=1/4.Give your answers correct to the nearest integers.

Homework Equations

:s

The Attempt at a Solution

do i just tap them in the calculator or how?

 

[Dick]

I would start by sketching a graph of the function first. You should be able to see that there are two possible values of theta. Then sure, use your calculator to find them.