Answer: sec x + C.
- A sec x + C
- B tan x + C
- C sec²x + C
- D cosec x + C
Correct answer: A. sec x + C
Explanation: d/dx(sec x) = sec x tan x. So integral of sec x tan x = sec x + C.
The exact area under the curve from a to b (shaded) is approximated by a few rectangles, the Riemann sum idea behind the definite integral.