Question

the base of this right prism is an equilateral triangle. the approximate height of the base is 15.6 cm. what is the approximate surface area of the prism?

Answer 1

Hello!

To find the surface area you can divide the prism into the 2D shapes it is made of

First list out all the shapes

2 triangles with bases of 18 and heights of 15.6
3 rectangles with side lengths of 20 and 18

First find the area of the triangles

The equation to find the area of a triangle is 

$A = \frac{hb}{2}$

A is area
h is height
b is base

Put in the values you know

$A = \frac{18 * 15.6}{2}$

Solve

A = 140.4

The triangles have an area of 140.4 units

Next we find the area of a the rectangles

To do this we multiply the sides

18 * 20 = 360

The rectangles have areas of 360 units

Now we add all the areas

There are 2 triangles and 3 rectangles

140.4 + 140.4 + 360 + 360 + 360 = 1360.8

The answer is B) 1360.8cm squared

Hope this helps!