112
A segment and its length
Textbook Part 4, pp. 4–5
GoalExpress a segment’s length in centimetres and decimetres; compare segments.
New words
length of a segment · kesma uzunligicentury · asrto restore · ta’mirlamoq
Explanation
A segment’s length is written in centimetres or decimetres: 25 cm = 2 dm 5 cm. To compare two segments, write both lengths in the same unit and compare the numbers.
Worked examples
The Bibi-Khanym mausoleum in Samarkand was ruined in the 19th century and restored at the end of the 20th: 20 − 19 = 1 century later.
AB = 1 dm, CD = 8 cm → 10 cm > 8 cm, so AB is longer.
Class activity
Each child draws any segment, measures it and writes it as “… dm … cm”. A classmate re-measures to check.
Practice
1
25 cm = ? dm ? cm
2 dm 5 cm
2
Put the sign: 1 dm 2 cm ... 15 cm
<
3
Put the sign: 3 dm ... 30 cm
=
4
24 girls and 23 boys went on a trip to Samarkand. How many in all?
47