Question:medium

A right triangle ABC with sides 5 cm, 12 cm and 13 cm is revolved about the side 12 cm. Find the volume of the solid so obtained.

Updated On: Jan 19, 2026
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Solution and Explanation

Step 1: Identifying the Solid Formed

When the right triangle is revolved about the side \( BC = 12 \, \text{cm} \), a cone is formed. The radius of the cone will be \( AB = 5 \, \text{cm} \), and the height of the cone will be \( BC = 12 \, \text{cm} \).

Step 2: Volume of the Cone

The formula for the volume \( V \) of a cone is: \[ V = \frac{1}{3} \pi r^2 h \] where \( r \) is the radius and \( h \) is the height of the cone. Substituting the values \( r = 5 \, \text{cm} \) and \( h = 12 \, \text{cm} \): \[ V = \frac{1}{3} \pi (5)^2 \times 12 = \frac{1}{3} \pi \times 25 \times 12 = \frac{1}{3} \pi \times 300 = 100 \pi \, \text{cm}^3 \] Therefore, the volume of the solid obtained is \( 100 \pi \, \text{cm}^3 \).

Conclusion:

The volume of the solid obtained by revolving the right triangle about the side \( BC = 12 \, \text{cm} \) is \( 100 \pi \, \text{cm}^3 \), which is approximately \( 314.16 \, \text{cm}^3 \) when using \( \pi \approx 3.1416 \).

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