If , then , remembering that your angles will be measured in radians. I have no idea why you are suggesting using inverse trigonometric functions.
If you need help evaluating the sec values, rewrite .
I have to find f'(x) and f'(1) for f(x) = cos(x) - 2tan(x)
f'(x) = -sin(x) - 2sec^2(x)
finding values of x I evaluate sin^(-1)(x), in this case sin^(-1)(1), am I right?
f'(1) = -sin(x) - 2sec^2(x) = -sin(x) - 2(1+ cot^2(1)) = -sin(1) - 2(1+ 1/tan^2(1)) = -1.570796327 - 2(1+1/0.616850275) = .....
I don't get where is my mistake, can someone show me?