the area of a whole circle is π(r+25)^2 solve.

Answer 1

pi(r+25)^2 = pi(r^2 + 50r +625) = pi(r)^2 +pi(50r) + pi(625)

this is similar to another posted question where a ring of stones of width 25 surrounds a circular flower bed of unknown radius, r.

pi(r+25)^2 is the area of the inner circle of radius r plus the area of the surrounding ring of stone of width 25 cm

subtract the inner circle from the total area of both to get the area of the ring of stones.

if the area of the stones is half the area of the flower bed, then the width times 4.45 = the radius. 4.45 x 25 = 111.25 cm