Find from the Definition of Derivative:
`f'(pi/4)` where `f(x)=secx`

Explanation

To find the derivative of the function \( f(x) = \sec x \) at \( x = \frac{\pi}{4} \) using the definition of the derivative, we will follow these steps:

### Step 1: Write the definition of the derivative
The derivative of a function \( f \) at a point \( a \) is defined as:
\[ f'(a) = \lim_{h \to 0} \frac{f(a + h) - f(a)}{h} \]
In our case, we need to find \( f'(\frac{\pi}{4}) \).
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