math
posted by soumitra on .
find the value
lim [sin(x+h)sinx]/h
h>0

There are many proofs of this, such as the one here:
http://www.wyzant.com/resources/lessons/math/calculus/derivative_proofs/sinx
However, it relies on the fact that sinx/x > 1 as x>0. That is usually proven as given here:
http://math.ucsd.edu/~wgarner/math20a/sin%28x%29_over_x.htm