Let us assume ………equation 1

By property, we know that

Thus

….....equation 2

Adding equation 1 and equation 1

We know

We know

Let cos x = y

Differentiating both sides

– sin x dx = dy

sinx dx = – dy

For x = 0

Cos x = y

Cos 0 = y

y = 1

for x = π

y = – 1

Substituting the given values

We know that

We know b and a being the upper and lower limits respectively