If the area of the base of a cone is 154 cm2 and the area of its curved surface is 550 cm2, then its volume is:
Answer & explanation
Correct answer: option 1
We know that,
Volume of cone = \(\frac{1}{3}\)πr2h
Curved surface area of cone = πrl
Area of base of cone = πr2
We have,
Area of base of cone = 154 cm2
Area of curved surface = 550 cm2
\(\frac{22}{7}\) × r2 = 154
= r2 = (154 × 7) × \(\frac{1}{22}\)
= r2 = 49
= r = 7 cm
Curved surface area of cone = 550 = \(\frac{22}{7}\) × 7 × l
l =25
Now, h = \(\sqrt {l^2 – r^2}\)
= h = \(\sqrt {25^2 – 7^2}\) = \(\sqrt {625 – 49}\)
= h = 24
Volume of cone = \(\frac{1}{3}\) × \(\frac{22}{7}\) × 7 × 7 × 24
= 22 × 7 × 8 = 1232 cm3