Question Number 103872 by mikolo last updated on 17/Jul/20

Commented bybramlex last updated on 18/Jul/20

Commented bybramlex last updated on 18/Jul/20

AB^2 = AD^2 + BD^2 (2+r)^2 = 4 + (4−r)^2 (2+r)^2 −(4−r)^2 = 4 (6)(2r−2) = 4 ⇒ r−1 = (1/3) ∴ r = (4/3) .

Commented bybramlex last updated on 18/Jul/20

the shaded area A= (1/2)π(4)^2 −π(2)^2 −π((4/3))^2 A= 8π−4π−((16π)/9) = ((20π)/9).