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Homework
Example 4 Find a perpendicular bisector
Write an equation for the perpendicular bisector of the
line segment joining A(24, 1) and B(2, 3).
Solution
1. Find the midpoint of the line segment.
1 x1 1 x2 }
2 , y1 1 y2 }
2 2 5 1
2. Calculate the slope of
, 2 5 ( , )
}
AB .
m 5 y 2 2 y 1
}
x 2 2 x 1 5 5 5
3. Find the slope of the perpendicular bisector.
2
1
} 5 5
m
4. Use point-slope form: y 2 5 (x 2 ( )) or
y 5 .
An equation for the perpendicular bisector of AB is
y 5 .
Checkpoint Complete the following exercises.
3. Find the midpoint of the line segment joining (26, 5)
and (1, 1).
4. Write an equation for the perpendicular bisector of
the line segment joining A(25, 6) and (3, 22).
234 Lesson 9.1 Algebra 2 Notetaking Guide Copyright © Holt McDougal. All rights reserved.