Page 82 - Math Course 1 (Book 2)

Midpoints of a Segment

Find Distance on a Coordinate Plane

Find the distance between A(–3, 4) and M(1, 2).

A. 4

B. 12

C. 20

D. 6

Answer

MO. 9 - L3b

Finding the Midpoint
of a Segment segment bisector

Any segment, line, or plane that intersects a
Vocabulary A-Z segment at its midpoint is called a segment
bisector.
Let us learn some vocabulary
A

N
M
midpoint D
The midpoint of a segment is the point on the
segment that divides the segment into two R B
congruent segments.
↔
M is the midpoint of AB. Plane N, MD, RM, and
A X B point M are all bisectors of AB. We say that they

If X is the midpoint of AB, then AX = XB. bisect AB.

Key Concept Midpoint
Words The midpoint M of PQ is the point between P and Q such that PM = MQ.
Symbols Number Line Coordinate Plane

The coordinate of the midpoint of a The coordinates of the midpoint of segment whose
segment with endpoints that have endpoints have coordinates (X , Y ) and (X , Y )
1
1
2
2
a + b ( X + X ) ( Y + Y )
2
1
2
1
coordinates a and b is are ( , ).
2
2 2
Models x
A M Q Q = (X , Y )
2 2
0 y
a b
a + b ( X + X ) ( Y + Y )
2
1
1
2
2 P = (X , Y ) M( , ).
1
1
2 2
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