Question

The curved surface area of a cone is $154{\text{cm}}^2$ and its slant height is 7 cm. Find the diameter of the cone. (Take $\pi =\frac{22}{7}$)

• A. 14 cm
• B. 7 cm
• C. 21 cm
• D. 28 cm

Answer 1

The correct option is A 14 cm

Lets draw a cone of given dimensions.
Let the radius be r.
For the cone given in the figure,
Radius $=rcm$
Slant height $=l=7cm$

Curved Surface Area (CSA) $=\pi rl$

$154=\frac{22}{7}\times r\times 7(\because CSA=154)$

$154=22r$

$r=\frac{154}{22}$

$=7$ cm

Diameter of a cone$=2\times 7=14$ cm