1-5
1-3 Using
UsingFormulas
FormulasininGeometry
Geometry
Lesson Presentation
Holt
Geometry
Holt
Geometry
1-5 Using Formulas in Geometry
1-3
Objective
1. Solve problems by using formulas.
2. Find maximum area of a rectangle
for a given perimeter.
Holt Geometry
1-5 Using Formulas in Geometry
1-3
Problem-Solving Plan: (1) Explore the problem. (2)
Plan the solution. (3) Solve the problem. (4) Examine
the solution.
Holt 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 Geometry
1-5 Using Formulas in Geometry
Example 1A: Finding Perimeter and Area
Find the perimeter and area of each figure.
= 2(6) + 2(4)
= 12 + 8 = 20 in.
= (6)(4) = 24 in2
Holt Geometry
1-5 Using Formulas in Geometry
Example 2
One type of pet enclosure is made up of 12 sections of fencing,
connected by hinges. This enclosure folds for easy storage and is
flexible for making different-sized areas in which your pet can play.
Suppose the sections are positioned to make a rectangle. What are
the dimensions of the rectangle that provide the maximum area for
your pet?
Holt Geometry
1-5 Using Formulas in Geometry
Example 3
A formula for computing simple interest is I = prt, where I is the interest
earned, p is the principal (or the amount of money invested), r is the
rate of interest (expressed as a decimal value), and t is the length of
time in years it is invested. Soledad offered to lend her younger
sister Lola $200 at a 3.5% interest rate. She told Lola that her loan
would cost Lola $217.50 at the end of the loan period. How long is
Soledad giving Lola to pay back the loan?
Holt Geometry
1-5 Using Formulas in Geometry
Homework
Pg.22-24 (1-9all, 16-38E)
Holt Geometry