Solve ${\int }_0^{\pi /2}\cos xdx$

Step-by-step solution

1. Step 1 · Find an antiderivative
   $$F(x)=\sin x$$

   The derivative of sine is cosine when angles are measured in radians.

2. Step 2 · Fundamental theorem of calculus
   $$F(\pi /2)-F(0)=1-0=1$$

   Evaluate at the upper limit and subtract the lower limit. A definite integral needs no added constant.