Please solve The lines y x2 and y 0 divide the unit disk x

Please solve

The lines y = x/2 and y = 0 divide the unit disk x^2 + y^2 le 1 into four pies. The area of the two smaller pies is 1/2 1/tan0.5. pi/4 1/2 tan^-1 0.5. pi/2.

Solution

Solution:

The angle between lines x/2 and y = 0 is arctan(0.5).   { y = x/2 => y/x = 1/2 => tan = 1/2 => = arctan(0.5)}

So the area of the two smaller pies is:
(arctan(0.5))/2 = arctan(0.5)/2

= (1/2) arctan(0.5)
Choose option C