The slant height of a cone is 5cm and the radius of its base is...
MATHEMATICS
WAEC 2013
The slant height of a cone is 5cm and the radius of its base is 3cm. Find, correct to the nearest whole number, the volume of the cone. ( Take \(\pi = \frac{22}{7}\))
- A. 48cm3
- B. 47cm3
- C. 38cm3
- D. 12cm3
Correct Answer: C. 38cm3
Explanation
Volume of a cone = \(\frac{1}{3} \pi r^2h\)
h2 = 52 = 32
= 25 - 9 = 16
h = \(\sqrt{16}\)
h = 4cm
v = \(\frac{1}{3} \times \frac{22}{7} \times 3^2 \times 4\)
\(\frac{1}{3} \times \frac{22}{7} \times 9 \times 4\)
= \(\frac{22 \times 3 \times 4}{7}\)
= 37.7cm3
= 38cm3
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