Given: Area of isosceles triangle = 360 cm²

Base of triangle = 80 cm

Let a be the equal sides of the triangle

We know that,

Area of isosceles triangle = 1/4 × b√(4a² – b²)

⇒ 360 = 1/4 × 80√(4a² – 80²)

⇒ 360 = 1/4 × 80√(4a² – 6400)

⇒ 360 = 20√[4(a² – 1600)]

⇒ 360 = 20 × 2√(a² – 1600)

⇒ 9 = √(a² – 1600)

On squaring both sides we get,

⇒ 81 = a² – 1600

⇒ a² = 1600 + 81 = 1681

⇒ a = 41 cm

Now,

Perimeter of triangle = 41 cm + 41 cm + 80 cm

= 162 cm