The blue area has an angle of 120 degrees, and 120/360 = 1/3, which shows that the blue area is 1/3 of the circle. In that case, the blue area is just 144pi/3. That simplifies to 48 pi.
First, we can factor all of the following equations to turn that weird, huge looking thing into ÷ × . We know that division is simply multiplication by the reciprocal, so that whole equation will turn into × × . Now we can cancel out some values if they are both in the numerator and denominator, which will turn that still huge looking thing into which is our final answer, as it cannot be simplified further.