Question

PLEASE HELP ME ASAP (picture attached)

7.
A circle with a radius of 9 cm is divided into five equal sectors.
The diagram shows one of the sectors, AOB.
The chord AB is drawn.
B
9 cm
A
72
Find the area of the shaded region.

Answer 1

im learning this in maths too but my maths teacher said

"tita=a times by πr²over 360 divided by angle then times by 18 cuz diameter=1 but radius is half of diameter

i am so sorry if this doesnt work