Question

The slant height of the frustum of a cone in 4cm and perimeter of its circular ends 18cm and 6cm. Find curved surface area of tje frustum

Answer 1

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Answer 2

Given :

The slant height of the frustum of a cone in 4cm and perimeter of its circular ends 18cm and 6cm.

To Find:

Find curved surface area of tje frustum

Solution:

Slant height of frustum = 4 cm

Perimeter of smaller circular end = 6 cm

So, $2 \pi r = 6 cm \\2 \times \frac{22}{7} \times r =6\\r=\frac{6 \times 7}{2 \times 22}\\r=0.95$

Perimeter of bigger circular end = 18 cm

$2 \times \frac{22}{7} \times R = 18\\R=\frac{18 \times 7}{2 \times 22}\\R=2.86$

Curved surface area of frustum = $\pi (r+R)l=\frac{22}{7}(0.95+2.86)4=47.89 cm^2$

Hence The curved surface area of frustum is 47.89 sq.cm.