Can someone explain the highlighted part, I don't understand the simplifications. And how do you find the interval of convergence for this question?

answer rather than having to add and subtract the measurements of the semi-circle, notice that the semicircle to the left of ad is actually identical in area to the blank semicircle-shaped space to the left of bc. so if we transferred the red semicircle into the blank space, we would end up with a square of side length 24 cm. the area of a square is s^2 = 24^2 = 676 cm^2.

u also answered this so i think u would know but i am here to

put in or use mine

v=1788.75

step-by-step explanation:

i belive that is the answer