Question

The figure below shows a circle centre O. Chord AB subtends 30° at the centre. If the area of the minor segment is 5.25cm², find the radius of the circle. 

Answer 1

 30   × 22 × r²  =  11 r²
360      7              42
Area of ∆ = ½r² sin 30 = ¼r²  
11 r² − ¼r² =5.25
42
84 × 1  r² =5.25 × 84
       84   
r² = 441
r² = √441
 r = 21cm