Answer:
[tex]Surface\text{ area of the regular pyramid = 648 sq units \lparen option A\rparen}[/tex]
Explanation:
Given:
The dimension of the base of the pyramid: 12 by 12
The slant height = 21
To find:
the surface area of the pyramid
To determine the surface area, we will apply the formula:
[tex]Surface\text{ area = Area + }\frac{1}{2}(perimeter)(slant\text{ height\rparen}[/tex][tex]\begin{gathered} The\text{ base is a square. } \\ \text{Area of the base = Area of the square} \\ \\ Area\text{ of the base = side}^2 \\ Area\text{ of the base = 12}^2\text{ = 144} \end{gathered}[/tex][tex]\begin{gathered} Perimeter\text{ of the base = 4\lparen side\rparen} \\ Perimeter\text{ of the base = 4\lparen12\rparen} \\ \\ \text{ Perimeter of the base = 48} \end{gathered}[/tex][tex]\begin{gathered} Surface\text{ area of the regular pyramid = }144\text{ + }\frac{1}{2}(48\times21) \\ \\ Surface\text{ area of the regular pyramid = 648 sq units \lparen option A\rparen} \end{gathered}[/tex]
