The Total solution for NCERT class 6-12
Given:Length AB = 40 cmDiagonal AC = 41 cmIn right triangle ABC, we haveAB2 + BC2=AC2 (By Pythagoras property)⇒ (40)2 + BC2 =(41)2⇒ 1600 +BC2 = 1681⇒ BC2 = 1681 – 1600⇒ BC2 = 81∴ BC == 9 cm
∴ AB =DC = 40 cm and BC = AD = 9 cm (Property of rectangle)∴ Therequired perimeter= AB + BC + CD + DA= (40 + 9 + 40 + 9) cm= 98 cm