[?] Solve the highlighted area?

[baajcom220 (Bayasgalan Bayasgalan)]

How can I solve highlighted area?

[mariuszi28cg (Mariusz Iwaniuk)]

Click here

[christopher (Christopher Wolfram)]

If you wanted to do that in Mathematica, you could write this,

Integrate[Cos[x], {x, -Pi/2, Pi/2}]

which returns 2.

[baajcom220 (Bayasgalan Bayasgalan)]

thanks you all.