Quincy folds a piece of cardboard to make the three sides of a triangular prism open at top
and bottom. The triangular prism and the piece of cardboard that he used are shown below.
What is the area of the piece of cardboard?

500 cm2

Step-by-step explanation:

The dimensions of the prism are 7 cm, 9 cm and 20 cm.

So the three areas we want to find are three rectangles, with the sides:

7 cm and 20 cm, 9 cm and 20 cm, 9 cm and 20 cm

The area of each rectangle is:

rectangle_1 = 7 * 20 = 140 cm2

rectangle_2 = 9 * 20 = 180 cm2

rectangle_3 = 9 * 20 = 180 cm2

Summing all these three areas, we have:

Total area = 140 + 180 + 180 = 500 cm2

i used to know how to do this in 7th but i forget easily

step-by-step explanation: