finding areas perimeters and segments in circle

Hi, i really need help on working this one out as it is very important for school, thanks in advance.

A circle has centre o and radius 1cm, points A,B,C,D,E and F lie on the cirumference, so that A,B,C,D,E,F is a regular hexagone(6 equal sides)

(a): Show that triangle OAB is equilateral, Find its area and the area of the hexagone. Find the area of the circle

(b) : deduce the area of the minor segment defined on AB

(c): Find perimeter of this segment