Cos^2(π/4): Why Does it Equal 1/2?

[CrossFit415]

cos^2(∏/4)

Why does this equal to 1/2? Doesn't Cos(Pi/4)= √2/2 ?

Thanks

 

[Villyer]

What is (√2/2)^2?

 

[eumyang]

$\cos^2 \frac{\pi}{4}$
$= \left(\cos \frac{\pi}{4}\right)\left(\cos \frac{\pi}{4}\right)$
$= \left(\frac{\sqrt{2}}{2}\right)\left(\frac{\sqrt{2}}{2}\right)$
$= ?$

 

[CrossFit415]

Opps! Haha, thank you both, I know understand cos pi 4 now.