Question

Hemisphere O with radius 6 cm is given in the figure on the picture. When rotating it 30 degrees with B, which is one end of the diameter AB, as the center of rotation, answer the following questions.

①Find the circumference of the shaded part


②Find the area of the shaded part



How do I solve this??? Please help ASAP!!!

Answer 1

1) Perimeter of shaded region =
`\pi r` +
`\pi r` *30/360
= 3.14*6 + 3.14*6/12 = 18.84 + 1.57 = 20.41 cm


2) Area of shaded region = CSA of hemisphere

2
`\pi r^2` = 2*3.14*36 = 226.08 cm^2