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: Recall triangle - area formula

The area formula for a triangle is $A=\frac{1}{2}bh$, where $b$ is the base and $h$ is the height.

Step2: Calculate area of one triangle

Given $b = 4$ cm and $h = 5$ cm, then $A=\frac{1}{2}\times4\times5=10$ $cm^{2}$.

Step3: Count number of triangles

The pyramid is composed of 4 congruent triangles.

Step4: Calculate surface - area of pyramid

The surface - area $S$ of the pyramid is the sum of the areas of the 4 triangles. So $S = 4\times A=4\times10 = 40$ $cm^{2}$.

Answer:

40 sq cm