semoga yg jawab diberi pahala

Keliling lingkaran = 2 x phi x r = 2 x 22/7 x 21 = 132 cm
Panjang busur = (besar sudut/1 putaran) x keliling lingkaran = [(360-90)/360] x 132 cm = (270/360) x 132 cm = 99 cm

Keliling bangun = panjang busur + (4 x 21) = 99 + 84 = 183 cm