Show that `f(x)=tan^(-1)(sinx+cosx)` is a decreasing function on the interval on `(pi//4,\ pi//2)` .

Explanation

To show that the function \( f(x) = \tan^{-1}(\sin x + \cos x) \) is a decreasing function on the interval \( \left(\frac{\pi}{4}, \frac{\pi}{2}\right) \), we need to follow these steps:

### Step 1: Find the derivative of the function \( f(x) \)

To determine whether the function is increasing or decreasing, we first find the derivative \( f'(x) \).

\[
f'(x) = \frac{d}{dx} \left( \tan^{-1}(\sin x + \cos x) \right)
...