Question

A conical birthday cap is 12cm high and base radius 5cm .find area of sheet required to make 20 such caps?

Answer 1

The area of sheet required to make 20 such caps is 5652 cm².

Step-by-step explanation:

Given, height of a conical cap = h = 12 cm

radius = r = 5 cm

Slant height of a cone = L = $\sqrt{r^{2}+h^{2} } = \sqrt{5^{2} +12^{2} } =\sqrt{25+144} =\sqrt{169} = 13$ cm

Surface area of a cone = $(\pi rL +\pi r^{2} ) = \pi r(L+r) = 3.14 \times 5 (13+5)= 15.7 \times 18 = 282.6$ cm²

Area of sheet required to make 1 cap = 282.6 cm²

Area of sheet required to make 20 such caps = 282.6 x 20 = 5652 cm²

Hence, the area of sheet required to make 20 such caps is 5652 cm².