basically what the topic states - derive the formula for the derivative of arctan x.
d/dx (arctan x) = 1/(1+x^2)
The Attempt at a Solution
strange question because we already know the answer. but im not sure how to start this.
i know arctan x = y
therefore tan y = x
but what can i do with this? do i need to draw a right triangle and label all the sides? can someone help me get started? thanks.