Question

If \[ \frac{d}{dx} \left( \frac{\sec x+\tan x} {\sec x-\tan x} \right) =k \] at \[ x=\frac{\pi}{4}, \] then \[ \frac{k}{2\sqrt2}-2\sqrt2= \ ?} \]

• A. \(5\sqrt2\)
• B. \(12\sqrt2\)
• C. \(3\)
• D. \(9\)

Hint:

Always look for trigonometric identities before differentiating complicated expressions.

Answer 1

The Correct Option is C