1-5 Using Formulas in Geometry
Objectives
Students will be able to apply perimeter,
area, and circumference formulas to
solve problem.
Holt McDougal Geometry
1-5 Using Formulas in Geometry
The perimeter P of a plane figure is
the sum of the side lengths of the
figure.
The area A of a plane figure is the
number of non-overlapping square
units of a given size that exactly
cover the figure.
Holt McDougal Geometry
1-5 Using Formulas in Geometry
Remember!
Perimeter is expressed in linear
units, such as inches (in.) or meters
(m).
Area is expressed in square units,
such as square centimeters (cm2).
Holt McDougal Geometry
1-5 Using Formulas in Geometry
Holt McDougal Geometry
1-5 Using Formulas in Geometry
The base b can be any side of a
triangle.
The height h is a segment forms a
right angle with the base. The height
may be a side of the triangle or in the
interior or the exterior of the triangle.
Holt McDougal Geometry
1-5 Using Formulas in Geometry
What’s my base and what’s my
height?
Holt McDougal Geometry
1-5 Using Formulas in Geometry
Perimeter and Area with Algebra
Find the area and perimeter of each figure.
1.
x2 + 4x; 4x + 8
2.
10x; 4x + 16
Holt McDougal Geometry
1-5 Using Formulas in Geometry
The circumference of a circle is the distance
around the circle.
“perimeter of the circle”
Holt McDougal Geometry
1-5 Using Formulas in Geometry
 (Pi) is often approximated as 3.14 or
Holt McDougal Geometry
.
1-5 Using Formulas in Geometry
Find circumference and area of circles
Find the area and perimeter of each circle.
1.
2.
Holt McDougal Geometry
1-5 Using Formulas in Geometry
Find Circumference and Areas of Circles
Holt McDougal Geometry
1-5 Using Formulas in Geometry
Find Circumference and Areas of Circles
Holt McDougal Geometry
1-5 Using Formulas in Geometry
1.5 HW answer
1.
2.
3.
4.
5.
6.
7.
8.
9.
10.
12 ft
6 ft2
2.4 ft or ft
P  9.6 m; A  5.76 m2
P  2x  20; A  7x  21
circumference
C  44 mi; A  154 mi2
2 in.
19 m
12.5 mm
Holt McDougal Geometry
1-5 Using Formulas in Geometry
Apply Formulas of Perimeter, Circumference and Areas
Holt McDougal Geometry
1-5 Using Formulas in Geometry
Apply Formulas of Perimeter, Circumference and Areas
Holt McDougal Geometry
1-5 Using Formulas in Geometry
Holt McDougal Geometry
1-5 Using Formulas in Geometry
Group wprk- Application in Real LIfe
A landscaper is installing a brick patio in the backyard. He is
building a rock wall around the perimeter of the patio.
1. What is the area needed for the brick patio?
2. What is the perimeter needed for building the brick wall?
28.56ft.
Holt McDougal Geometry