The surface area is the sum of all the faces.
Area of a Triangle = 1/2 x base x height
Area of a Rectangle = base x height
First, we'll find the area of the two triangles.
base = 10
height = 4
A = 1/2 x 10 x 4 = 20
Since we have two triangles, we'll need to double this number.
20 x 2 = 40
Next, we'll find the areas of the three rectangular sides.
A = 8 x 9 = 72
A = 5 x 9 = 45
A = 10 x 9 = 90
Now that we know all of the areas of the faces, all that's left to do is add them up.
Surface Area = 40 + 72 + 45 + 90 = 247
Answer: 247 cm^2
Hope this helps!
