# Trigonometry/Derivative of Sine

From Wikibooks, open books for an open world

To find the derivative of sin(θ).

- .

Clearly, the limit of the first term is since is a continuous function. Write *k* = ^{h}⁄_{2}; the second term is then

- .

Which we proved earlier tends to 1 as .

And since

- ,

the limit of the second term is 1 too. Thus

- .