Page 125 - Math Course 1 (Book 2)

Geometric Area: Parallelogram

Mo. 10

Lesson 4 Base and Each pair of opposite sides of a

Side parallelogram has the same
measure. Each base is 32 inches
long, and each side is 24 inches
KEY CONCEPTS: long.
1. Find perimeters and areas of
parallelograms. Perimeter The perimeter of a polygon is the
2. Determine whether points on a coordinate sum of the measures of its sides. So,
plane def ne a parallelogram. the perimeter of ▱RSTU is 2(32)
+ 2(24) or 112 inches.

Height Use a 30°-60°-90° triangle to f nd the
MO. 10 - L4a
height. Recall that if the measure of
Perimeters and Areas the leg opposite the 30° angle is x,
of Parallelogram then the length of the hypotenuse is
2x, and the length of the leg opposite
the 60° angle is x .
3
Key Concept
2 = 2x Substitute 24 for the
hypotenuse.
Area of Parallelogram 12 = x Divide each side by 2.

Words If a parallelogram has an area of A
3
square unit, and a height of h unit, then So, the height of the parallelogram is x or
area equals the product of the base and 12 inches.
3
the height.
Area A = bh Area of a
Symbols A = bh h parallelogram
3
= 32 (12 ) b = 32, h = 12 3
3
b = 384 or about 665.1

The perimeter of ▱RSTU
Let’s Begin Answer is 112 inches, and the area is
about 665.1 square inches.

Perimeter and Area of a Parallelogram Real World Example

Examples The Kanes want to sod a portion of their yard.

Find the number of square yards of grass needed
Find the perimeter and area of ▱RSTU to sod the shaded region in the diagram.

R S

24 in. 30°

U 32 in. T

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