Please help me on calculus: theorem

Question

Evaluate 

Options:

1. 1
2. 1/5
3. 5
4. -5

Answer 1

lim_θ→0 [(sinθ)/θ] = 1

So, lim_x→0 [(sin(10x) / (2x)] = (1/2)lim_x→0 [10sin(10x) / (10x)] = 5lim_x→0 [(sin(10x)) / (10x)] = 5(1) = 5