SOLUTION
Using Pythagoras' theorem , 
r^ 2 = 24 ^2 + 10 ^2 
r ^2 = 576 + 100
r ^2 = 676
Square root both sides, we have :
r = 26 m
Area of the shaded portion = Area of circle - Area of Rectangle
 = pi x r ^2 - ( L X W )
 = 22/ 7 X 26 x 26 - ( 24 x 10 ) 
 = 2124 4/ 7 - 240
 = 1884 4/7 m^2