First of all, relax :)
We'll get through this together, okay?
#38, finding the surface area of a prism, all you need to remember is, all three-dimensional shapes are made up of two-dimensional shapes.
So, one of the sides is 5 in. by 6.5 in. So, 5*6.5=32.5 square inches. But remember, there's another square just like this on the other side. So, multiply 32.5 by 2.
32.5*2=65 square inches.
Another square is 7.5 by 6.5
7.5*6.5=48.75
*2
48.75*2=97.5 square inches
One more set:
There's the top and bottom:
7.5 by 5
7.5*5=37.5
*2
37.5*2=75 square inches
So, add all of those up:
65 square inches+97.5 square inches+75 square inches=237.5 square inches.
So, surface area of the prism is
237.5 square inches.
Surface area of the triangular prism is the same. Just find the area of all the shapes.
There are two rectangles that are each 8cm by 5cm.
8*5=40 square cm
*2 (because there are two rectangles).
40*2=80
80 square cm
There is only one rectangle that is 8cm by 6cm (on the bottom), so just multiply the sides.
8*6=48 square cm
Finally, calculate the front and back triangles:
5cm*6cm=30 square cm
divide by 2 (because it's a triangle)
30/2=15 square cm
Then the other triangle, which is just another 15 square cm
15+15=30 square cm
Add up the areas:
48 square cm+80 square cm+30 square cm=158 square cm
Area of the triangular prism is 158 square centimeters.
