43
Distance between points on a ray
Textbook: Part 2, lesson 43, pp. 13–15
GoalFind the distance between two points on a coordinate ray.
New words
larger coordinate · katta koordinatasmaller coordinate · kichik koordinatalength of a segment · kesma uzunligito the right · o‘ng tomon
Explanation
To find the distance between two points we subtract the smaller coordinate from the larger. For A(3) and B(11), AB = 11 − 3 = 8 unit segments, i.e. 8 e. If e = 2 cm, AB = 8 × 2 = 16 cm. To find a coordinate we also add or subtract: to the right the coordinate is larger, to the left it is smaller.
Worked examples
A(4), B(13): AB = 13 − 4 = 9 e.
N is 7 e to the right of M(6): N(6 + 7) = N(13); P is 4 e to the left of M: P(6 − 4) = P(2).
Class activity
“Find the distance”: one child puts two points on a ray, the partner calculates the distance from the coordinates and then checks it with a ruler.
Practice
1
How many unit segments are there between A(4) and B(13)?
9
2
e = 5 km, the points are C(2) and D(9). How many km is CD?
35
3
N is 7 unit segments to the right of M(6). What is the coordinate of N?
13
4
L is 9 unit segments to the left of K(15). What is the coordinate of L?
6