A slice of a round cake is a sector of radius 21 cm with an angle of 60° at the centre. What is the area of the top of the slice? Take $\pi = \frac{22}{7}$ .

231 cm²Correct answerYour answer462 cm²Correct answerYour answer693 cm²Correct answerYour answer1,386 cm²Correct answerYour answer

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CorrectNot quiteAnswer A

Correct answer: A

Sector area = $\frac{\theta}{360^\circ} \times \pi r^2$ .
= $\frac{60}{360} \times \frac{22}{7} \times 21 \times 21 = \frac{1}{6} \times 1386 = 231$ cm².

Worth noting

462 cm² uses 120° in place of 60°, 693 cm² is a semicircle and 1,386 cm² is the whole cake. A 60° slice is one-sixth of it.

Ten questions from Mensuration: Areas and Volumes, at your own pace.

Ten questions from Mensuration: Areas and Volumes, at your own pace.

A slice of a round cake is a sector of radius 21 cm with an angle of 60° at the centre. What is the area of the top of the slice? Take π=227\pi = \frac{22}{7}π=722​.