What’s are the answers for parts A and B

You are constructing a histogram for scores that range from 70 to 100 in whole points. frequencies range from 3 to 10; that is, every whole-point score between 60 and 100 occurs at least 3 times, and at least one score occurs 10 times. which of these would probably be the best range and size for the score intervals along the x-axis?

Find the cosine function that is represented in the graph.

Gh bisects fgi. find the measure of hgi •15° •21° •10° •8°