Question

the base of each triangle is 4 cm and the height is 5 cm. what is the surface area of the pyramid? 20 sq cm 40 sq cm 36 sq cm 80 sq cm

Explanation:

Step1: Calculate the area of one triangle

The formula for the area of a triangle is \(A=\frac{1}{2}\times base\times height\). Given \(base = 4\space cm\) and \(height=5\space cm\), then \(A=\frac{1}{2}\times4\times5 = 10\space cm^{2}\)

Step2: Count the number of triangular faces

From the figure, we can see there are \(4\) congruent triangular faces.

Step3: Calculate the surface area of the pyramid

The surface area \(S\) of the pyramid (sum of the areas of all triangular faces) is \(S = 4\times A\). Substitute \(A = 10\space cm^{2}\), we get \(S=4\times10=40\space cm^{2}\)

Answer:

40 sq cm