Let us assume
I = \(\int\limits_{0}^{\pi/2}\cfrac{1}{1+cot\text x}d\text x \)....equation 1
We know that tan x = \(\cfrac{cos\text x}{sin\text x}\)
cot x = \(\cfrac{1}{tan\text x}\)
Substituting the value in equation 1 we have,

By property, we know that

Thus in equation 2


Adding equation 2 and 3

Thus
