i. Let ABCD be the rhombus.
AC = 20 cm, BD = 21 cm
ii. In ∆AOB, ∠AOB = 90° [Diagonals of a rhombus are prependicular to each other]
∴ AB = AO + BO [Pythagoras theorem]
iii. Perimeter of ABCD
= 4 x AB = 4 x 14.5 = 58 cm
∴ The side and perimeter of the rhombus are 14.5 cm and 58 cm respectively.
