Multiple choice

The lateral area of the frustum of a right circular cone is calculated by using the formula _________________.

  1. $\displaystyle \frac{1}{2} (2\pi R + 2\pi r) l$
  2. $\displaystyle \frac{1}{2} (2\pi R - 2\pi r) l$
  3. $\displaystyle \frac{1}{2} (2\pi R + 2\pi r) $
  4. $\displaystyle \frac{1}{3} (2\pi R + 2\pi r) l$
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A Correct answer
Explanation

The lateral area of a frustum is the average of the circumferences of the two bases multiplied by the slant height: (2*pi*R + 2*pi*r)/2 * l = pi(R+r)l.

AI explanation

The lateral surface area of a frustum is found by taking half of the sum of the circumferences of the top and bottom bases and multiplying it by the slant height. The circumference of a circle is 2 times pi times its radius. Thus, the formula is written as 1 over 2 multiplied by (2 times pi times R plus 2 times pi times r) and l.

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