Question

PLEASE HELP, NO LINKS, 7TH GRADE MATH.

Jada is using pyramid-shaped piece of foam with the dimensions shown below for a model she is making. She has to paint the triangular surfaces for her model. The slant height of each triangular face is 9mm. The base will NOT be painted. Find the SURFACE AREA of the pyramid that has to be painted.

Answer 1

The answer is 90 mm squared

Explanation:

First off, Surface Area is the combined areas of the 2D shapes that make up a 3D shape. The formula for finding the area of a triangle (the 2D shape that makes up most of a pyramid) is a = 1/2 bh, which is basically area = 1/2 base (the un-slanted line) * the height, or the middle line.

Since there are 4 triangles, you would multiply this by 4 after solving, so

sa = 4(1/2bh)

Putting the numbers in, you'd get

sa = 4(1/2*5*9)

To solve:

sa = 4(1/2*45)

sa = 4(22.5)

sa = 90mm^2