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 13 Page 818

Use the formula for the surface area of a prism.

Lateral Area: 11.2 m^2
Surface Area: 13.6 m^2

Practice makes perfect

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

We will do these things one at a time.

Lateral area

Let's recall the formula for the lateral area L of a prism. L=Ph Here, P is the perimeter of the base, and h the height of the prism. Note that the base is a triangle. We see in the diagram that the lengths of the legs of this triangle are 2.4m, 1.5m and 1.7 m. Let's add them to find its perimeter. P&= 2.4+ 1.5+ 1.7 P&= 5.6m Let's now substitute P= 5.6 and h= 2 in the formula for the lateral area of a prism.
L=Ph
L= 5.6( 2)
L=11.2
The lateral area of the solid is 11.2 m^2.

Surface Area

Let's recall the formula for the surface area of a prism. S=L+2B Here, L is the lateral area of the prism and B the area of the base. We already know that L=11.2m^2. We can calculate the area of the base using the formula for area of a triangle.
B=1/2bh
B=1/2( 2.4)( 1)
Evaluate right-hand side
B=2.4/2
B=1.2
The area of the base is 1.2m^2. Now we have enough information to find the surface area of the prism. Let's substitute 11.2 and 1.2 for L and B, respectively, into the corresponding formula and simplify.
S=L+2B
S=11.2+2(1.2)
Evaluate right-hand side
S=11.2+2.4
S=13.6
The surface area of the prism is 13.6m^2.