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Class 6 Lines and Angles: cheat sheet
CBSE Mathematics. Points, lines, line segments and rays, the kinds of angles, turns and directions, and the angles made by the hands of a clock.
Key ideas
- A line goes on forever both ways; a line segment has two end points; a ray has one end point and goes on forever the other way.
- An angle is made by two rays from the same point (the vertex); its size is how much one arm turns to reach the other.
- A full turn is 360°, a half turn 180° and a quarter turn 90°.
- Acute: less than 90°. Right: 90°. Obtuse: between 90° and 180°. Straight: 180°. Reflex: more than 180°.
- North, East, South and West are a quarter turn (90°) apart.
Remember
| Hour hand | 30° for every hour; ½° for every minute |
| Minute hand | 6° for every minute; one full turn every hour |
| Turns | ¼ turn = 90°; ½ turn = 180°; full turn = 360° |
Watch out
- Reading the wrong scale on a protractor (start from the 0 on the arm).
- Thinking the hour hand stays still while the minutes pass.
- Calling a 180° angle obtuse (it is a straight angle).
Worked example
School starts at 7 o'clock in the morning and ends 4 hours later. Through how many degrees does the hour hand turn during the school day, and through how many full turns does the minute hand go?
Working: 4 × 30° = 120°; the minute hand makes one full turn every hour (ends at 11 o'clock)
Answer: 120°; 4 full turns
Practise Lines and Angles
Revise with this page, then practise: every Lines and Angles sheet in the app is new, with an answer key and working.
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