Find the perimeter of each of the following shapes : 

(a) A triangle of sides 3 cm, 4 cm and 5 cm. 

(b) An equilateral triangle of side 9 cm. 

(c) An isosceles triangle with equal sides 8 cm each and third side 6 cm

We know that the perimeter of any figure represents the sum of its all side.

(a) Perimeter of triangle = 3 + 4 + 5

= 12 cm

Hence the perimeter of the triangle is 12 cm.

(b) Perimeter of an equilateral triangle = 3 × side

= 3 × 9

= 27 cm

Hence the perimeter of the equilateral triangle is 27 cm.

(c) Perimeter of isosceles triangle = 8 + 8 + 6

= 22 cm

Hence the perimeter of the isosceles triangle is 22 cm.