not sure how to do "a"

Problem 1. Let 1 _ 9(3) sin(5) .7; 7E 0 ag) _ {0 a; = 0 where g is differentiable at a: = 0 with 9(0) 2 g'(0) = 0. Show that f is also differentiable at :1: = 0 and nd f'(0). (You may either prove it in your own way or use the road map below.) (a) Use the denition of f to write out the difference quotient of f at .7; = 0, i.e. what is \"DMZ\"0)? (b) Try to nd a lower bound and an upper bound for the absolute value of the difference quotient in part (a). (Remember |sin(c)| S 1 for all c E R) (c) Use pinching theorem to show limh_,0 lMh-MQZI exists. What is the limit? What does this tell you about f'(0)