The perimeter of the figure given below is 15 cm. Find the length of the third side.
4 cm
Given : Perimeter of the given figure = 15 cm
Let the length of the third side be x.
Perimeter of a figure = Sum of lengths of its sides = AB + BC + AC
⇒ 15 cm = 6 cm + 5 cm + x
⇒ 15 cm = 11 cm + x
⇒ x = 15 cm - 11 cm
⇒ x = 4 cm
Therefore, the third side is 4 cm long.