Question

find area of segment with central angle 120 degree and radius 21 cm.

Answer 1

area of segment = 462 cm 2
area of triangle = 1/2 x b x h
                           = 1/2 x 21$\sqrt{} 3$ x 21/2 
                           = 441$\sqrt{3}$ / 4
area of segment = 462 - 441 x 1.73/4 
                              = 462- 190.7
                              = 271.3 cm2