A right pyramid stands on a square base of diagonal 10√2 cm. If the height of the pyramid is 12 cm, the area (in cm2) of its slant surface is

Answer: Option D

Solution

Answer: Option D

Solution:

$$\begin{array}{rl}& \text{Side of square}=\frac{1}{\sqrt{2}}\times 10\sqrt{2}=10\text{ cm}\\ & \text{Slant height}=\sqrt{5^2+{12}^2}=13\text{ cm}\\ & \text{Lateral surface area}\\ & =\frac{1}{2}\times \text{Perimeter of base}\times \text{Slant height}\\ & =\frac{1}{2}\times 40\times 30\\ & =260\text{ c}{\text{m}}^2\end{array}$$