Question

What is the surface area of the regular pyramid below?

Answer 1

Answer:

648 sq units

Step-by-step explanation:

Area of the base= 12×12= 144 sq. units

Perimeter of the base=4×12= 48

Total surface area= 1/2×48×21 + 144

=648 sq units

Answer 2

ANSWER

648 square units.

EXPLANATION

The surface area of the regular pyramid is the area of the base plus the area of the 4 triangular faces.

We use the formula;

$S.A = {l}^{2} + 4 \times \frac{1}{2} bh$

where l=12 units is the length of the square base and h=21 units is the vertical height of the triangular faces.

We substitute the values to get;

$S.A = 12^{2} + 4 \times \frac{1}{2} \times 12 \times 21$

$S.A = 144+ 504$

$S.A =648 {units}^{2}$