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?

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 is area
h is height
b is base

Put in the values you know



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!

The decimal expansion would be .27 repeated