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McGraw Hill Glencoe Geometry, 2012

MH

McGraw Hill Glencoe Geometry, 2012 View details

6. Two-Dimensional Figures

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Exercise 20 Page 62

Use the formulas for perimeter and area of a triangle.

Perimeter: $33 ft$
Area: $20 ft^{2}$

Practice makes perfect

Let's calculate the perimeter and area separately.

Perimeter

The perimeter of a figure is the sum of the side lengths. For a triangle, this is the sum of sides

a,

b,

and

c .

P = a + b + c

To calculate

P,

we should substitute the given values

a = 5,

b = 12,

and

c = 16

into the formula and simplify.

P = a + b + c

SubstituteValues

Substitute values

P = 5 + 12 + 16

Add terms

P = 33

The triangle's perimeter is

33 ft .

Area

Here we will use the formula for calculating the area of a triangle.

A = \frac{1}{2} b h

In this formula,

b

is the base and

h

is the height of a triangle. Now we substitute the value of the base,

b = 5,

and the value of the height,

h = 8,

into the formula to calculate

A .

A = \frac{1}{2} b h

$b = 5$ , $h = 8$

A = \frac{1}{2} (5) (8)

CommutativePropMult

Commutative Property of Multiplication

A = \frac{1}{2} (8) (5)

MoveRightFacToNumOne

$\frac{1}{b} \cdot a = \frac{a}{b}$

A = \frac{8}{2} \cdot 5

Calculate quotient

A = 4 \cdot 5

Multiply

A = 20

The area of the triangle is

20 ft^{2} .

Subchapter links

Check Your Understanding p.61

Practice and Problem Solving p.61-63

H.O.T. Problems p.63

Standardized Test Practice p.64

Spiral Review p.64

Skills Review p.64