Question

The lateral surface area of a prism is $378$ sq m and its height is $12$m. If the base is a regular nonagon, then find the length of each side of the base.
Note: Regular nonagon is a nine-sided polygon with all equal sides.

• A. $3.8$ cm
• B. $2.8$ cm
• C. $2.5$ cm
• D. $3.5$ cm

Answer 1

The correct option is D $3.5$ cm

Let $“x”$ be the length of each side of the nonagon.
Lateral surface of the prism $=9\times$Area of each rectangular face
$378=9\times (12\times x)$
$x=\frac{378}{9\times 12}=\frac{7}{2}=3.5$ cm