# Cos theta=pi/2 hint pi/2 is not an angle.

cos theta=pi/2....hint pi/2 is not an angle.

## Homework Statement

$$\cos\theta=\frac{\pi}{2}$$ HINT:The real number $\frac{\pi}{2}$ is not an angle.

## The Attempt at a Solution

I tried $0=\cos^{-1} \frac{\pi}{2}$, but that equals no solution.
And if $\frac{\pi}{2}$ were an angle the answer would be 0.

Am I solving this correctly?

SammyS
Staff Emeritus
Homework Helper
Gold Member

What is an approximate value for π/2 numerically?

$\pi \approx 3.14$ so $\frac{\pi}{2}\approx 1.57$

and since $\cos\theta=1.57, then...\theta=no solution, because: \cos\theta= -1\leq\theta\geq1$

uart

Hi jrjack. Are you at all familiar with complex numbers?

I'm not sure, but NO SOLUTION is always one of the possible options.

Please explain further how to use complex numbers in this problem.

rock.freak667
Homework Helper

I'm not sure, but NO SOLUTION is always one of the possible options.

Please explain further how to use complex numbers in this problem.

You might want to say no real solutions instead though.

Of course, No Real Solution. Since we are not dealing with imaginary numbers in this lesson, I think that is appropriate. Thanks.

uart