Find the locus:

What is the equation of the locus of points equidistant from the lines x = -4 and x = 2?

x = -1

Compound Locus

Geometry

Unit 7, Day 5

Mr. Zampetti

Objective:

To learn how to find the a compound locus

Definition

Compound Locus – a problem involving two or more locus conditions occurring at the same time

These different conditions are usually separated by “and” or “and also”

Problem:

A treasure is buried in your backyard.  A dog house is 8 feet from a stump and 18 feet from the tree.  The treasure is equidistant from the dog house and the tree AND ALSO 6 feet from the stump.  Locate all possible points of the buried treasure.

Solving Compound Locus Problems Step 1: Draw the diagram showing the

information in the problem.

Problem:

A treasure is buried in your backyard.  A dog house is 8 feet from a stump and 18 feet from the tree.  The treasure is equidistant from the dog house and the tree AND ALSO 6 feet from the stump.  Locate all possible points of the buried treasure.

8 ft.18 ft.

Solving Compound Locus Problems Step 1: Draw the diagram showing the

information in the problem. Step 2: Read to determine one of the

needed conditions.

Problem:

A treasure is buried in your backyard.  A dog house is 8 feet from a stump and 18 feet from the tree.  The treasure is equidistant from the dog house and the tree AND ALSO 6 feet from the stump.  Locate all possible points of the buried treasure.

8 ft.18 ft.

Solving Compound Locus Problems Step 1: Draw the diagram showing the

information in the problem. Step 2: Read to determine one of the

needed conditions. Step 3: Plot the 1st Locus Condition

Problem:

A treasure is buried in your backyard.  A dog house is 8 feet from a stump and 18 feet from the tree.  The treasure is equidistant from the dog house and the tree AND ALSO 6 feet from the stump.  Locate all possible points of the buried treasure.

8 ft.18 ft.

Solving Compound Locus Problems Step 1: Draw the diagram showing the

information in the problem. Step 2: Read to determine one of the

needed conditions. Step 3: Plot the 1st Locus Condition Step 4: Repeat steps 2&3 until all

conditions are satisfied.

Problem:

A treasure is buried in your backyard.  A dog house is 8 feet from a stump and 18 feet from the tree.  The treasure is equidistant from the dog house and the tree AND ALSO 6 feet from the stump.  Locate all possible points of the buried treasure.

8 ft.18 ft.

Problem:

A treasure is buried in your backyard.  A dog house is 8 feet from a stump and 18 feet from the tree.  The treasure is equidistant from the dog house and the tree AND ALSO 6 feet from the stump.  Locate all possible points of the buried treasure.

8 ft.18 ft.

Solving Compound Locus Problems Step 1: Draw the diagram showing the

information in the problem. Step 2: Read to determine one of the needed

conditions. Step 3: Plot the 1st Locus Condition Step 4: Repeat steps 2&3 until all conditions

are satisfied. Step 5: Place an X where the lines intersect,

these are the points that answer the compound locus.

Problem:

A treasure is buried in your backyard.  A dog house is 8 feet from a stump and 18 feet from the tree.  The treasure is equidistant from the dog house and the tree AND ALSO 6 feet from the stump.  Locate all possible points of the buried treasure.

8 ft.18 ft.

Practice 1:

Parallel lines r and s are 8 meters apart, and A is a point on line s.  How many points are equidistant from r and s and also 4 meters from A? 

A

r s

8m

4m

Practice 2:

A given point P is 10 units from a given line.  How many points are 3 units from the line and 5 units from point P?

P

10 units

3 un.3 un.5 units

Homework

Work Packet: Compound Locus