Given: Diagonals AC = 30 cm and DB = 16 cm.
Since the diagonals of the rhombus bisect at right angle to each other.
Therefore, OD = DB/2 = 16/2 = 8cm
And OC = AC/2 = 30/2 = 15 cm
Now, In right angle triangle DOC,
(DC)² = (OD)² + (OC)² [By Pythagoras theorem]
⇒ (DC)² = (8)² + (15)²
⇒ (DC)² = 64 + 225 = 289
⇒ DC = √289 = 17
Perimeter of rhombus = 4 x side = 4 x 17 = 68 cm
Thus, the perimeter of rhombus is 68 cm.

Class 7 Maths Chapter 6 Exercise 6.5

for more answers vist to:
https://www.tiwariacademy.com/ncert-solutions/class-7/maths/chapter-6/