Another question about differentiating a trigonometric function except I was away when they taught how to do it and I really am very bad at it.

a) Find the equation of the tangent to the curve y = sinx at the originI know this should be pretty straight foward but as I said I'm really bad at this kind of stuff.

b) Using a graph or otherwise, state the number of solutions to the equation sinx = x

c) Let m be a positive number. For what set of values does the equation sinx = mx have exactly 3 solutions satisfying-π ≤ x ≤ π

[I'm not sure if this is only my computer but those signs there on the last line should be pi's because on my computer some weird symbol is coming up]