In the following question, k =0.5.

http://img19.imageshack.us/img19/3323/cma3q11.gif

I know how to prove the function but am unsure which part is the answer. Any help?

-1 ≤ sin(1/2x) ≤ 1, for any x ≠ 0

-xsqr ≤ xsqr sin(1/2x) ≤ xsqr, for any x ≠ 0

g(x)[= -xsqr] ≤ f(x) ≤ [xsqr =]h(x), for any x ∈ ℝ

As the functions satisfied all 3 conditions of the squeeze rule, f is continuous at 0.

p/s: Sorry, i can't seem to get the square symbol working properly.