McGraw Hill Integrated II, 2012
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McGraw Hill Integrated II, 2012 View details
2. Surface Areas of Prisms and Cylinders
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Exercise 45 Page 821

Use the formula for the surface area of a prism.

A

Practice makes perfect

We are asked to find the lateral area and surface area of the given prism.

Let's recall the formula for the surface area of a prism S. S=Ph+2B Here, P is the perimeter of the base, h is the height, and B is the area of the base. Let's start by finding the perimeter of the base. We know that the base is a rectangle with length 15cm and width 4cm. Its perimeter is twice the sum of these two numbers. P=2( 15+ 4) ⇔ P = 38cm Now, we can calculate the area of the base using the formula for the area of a rectangle.
B= l w
B=( 15)( 4)
B=60
The area of the base is 60cm^2. We also know that the surface area of the solid is 310cm^2. With this information, we can find the height of the prism.
S=Ph+2B
310=( 38)(h)+2( 60)
Evaluate right-hand side
310=38h +120
190=38h
190/38=h
5= h
h=5
The height of the prism is 5 cm. Therefore, the correct answer is A.