Question

3. Find the derivative of x tan x, by first principle. ​

Answer 1

Answer:

To find the derivative of tan x,

we assume that f(x) = tan x.

Then by first principle, its derivative is given by the following limit.

Since f(x) = tan x, we have f(x + h) = tan (x + h).

By sum and difference formulas, sin A cos B - cos A sin B = sin (A - B).