"Suppose F is a continuous function at all point in the interval [0,1]. Also, suppose that all b<1 there is some x so that 0 1 and sin(f(x))> b. "

This sentence is part of the intermediate value theorem's proof question.

I want to do the proof by myself, but I don't understand the above sentence.(Especially the second sentence, I never seen sin(F(x)), and what is b?)

Can you please explain the sentence to me more intuitively by using graphs or words? Thanks. Neat writing pls.