For a frustum with end radii 19 cm and 7 cm and vertical height 16 cm, a student wrote the curved surface area as \π × 16 × 26 . What is wrong with that?

Question

Accepted Answer

The height 16 cm was used where the slant height 20 cm belongs. CSA = \π l (R + r) , and l = √16^2 + (19 - 7)^2 = √256 + 144 = 20 cm, so the correct expression is \π × 20 × 26 . The (R + r) = 26 part is right - the curved surface genuinely uses the SUM of the radii - and \π does belong. The single error is substituting h for l.

For a frustum with end radii 19 cm and 7 cm and vertical height 16 cm, a student wrote the curved surface area as $π \times 16 \times 26$ . What is wrong with that?

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More Class 10 Frustum of a Cone practice

For a frustum with end radii 19 cm and 7 cm and vertical height 16 cm, a student wrote the curved surface area as π×16×26. What is wrong with that?

Step-by-Step Solution

Master this chapter in 30 minutes a day.

More Class 10 Frustum of a Cone practice

For a frustum with end radii 19 cm and 7 cm and vertical height 16 cm, a student wrote the curved surface area as $π \times 16 \times 26$ . What is wrong with that?