Section 3 - Calculations
This section shows the rules for finding the distance between geometric objects.
The distance between two points is always the length of a straight line between them.
The distance between a point and a line is always the length of a straight line from the point to the line and also being perpendicular to the first line.
The distance from a point to a plane is always the length of a line extending from the point to the plane, with the line being perpendicular to the plane.
One of the ways to find the distance between two points is using a number line. A number line makes it easy to find the distance between two points on the line. When a point is placed on the line, it is given a numerical value. This number is also called a coordinate. The distance between two points can be found be finding the positive difference of the points' coordinates. Number lines can also be used to find the coordinate of a line's midpoint.
Find the distance between A and B.
A = -7
B = 6
6 - (-7) = 13
The distance between A and B is 13.
Find the coordinate of the midpoint of segment AB.
A = -7
B = 6
(6 + (-7))/2 = -.5
-.5 is the coordinate for the midpoint of segment AB.
Practice! Practice! Practice!
Use this picture for questions 1 - 8.
Name the line segment whose length is the distance between the following points.
1) A and B
2) B and C
3) E and D
4) F and C
Name the segment that is the distance between each point and line.
5) A and DE
6) D and AB
7) G and CF
8) E and AB
Use this drawing for numbers 9 - 11
Find the distance between the points
12) E and A
13) F and B
14) E and D
15) C and B
16) F and A
Find the coordinate of the midpoint of each segment
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