How do you find the solution to 25cos^2theta-4=0 if 0<=theta<360?

1 Answer
Dec 2, 2016

The value of the angle theta is cos^(-1)(+-2/5).

Explanation:

The givenequation is 25cos^2theta-4=0.
:.25cos^2theta=4.

:.cos^2theta=4/25.

:.cos theta=+-2/5.

Now, the range of cosine of a certain angle is:
-1<=costheta<=+1.

So, the above value of cosine of the angle, theta is true for certain values of theta.

:.theta=cos^(-1)(+-2/5). (Answer).