Chapter 5: Understanding Elementary Shapes

We know that in one complete clockwise revolution, hour hand will rotate by 360⁰

(a) When hour hand goes from 3 to 9 clockwise, it will rotate by 2 right angles or 180⁰

∴ Fraction = 180⁰ / 360⁰

= 1 / 2

(b) When hour hand goes from 4 to 7 clockwise, it will rotate by 1 right angle or 90⁰

∴ Fraction = 90⁰ / 360⁰

= 1 / 4

(c) When hour hand goes from 7 to 10 clockwise, it will rotate by 1 right angle or 90⁰

∴ Fraction = 90⁰ / 360⁰

= 1 / 4

(d) When hour hand goes from 12 to 9 clockwise, it will rotate by 3 right angles or 270⁰

∴ Fraction = 270⁰ / 360⁰

= 3 / 4

(e) When hour hand of a clock goes from 1 to 10 clockwise, it will rotate by 3 right angles or 270⁰

∴ Fraction = 270⁰ / 360⁰

= 3 / 4

(f) When hour hand goes from 6 to 3 clockwise, it will rotate by 3 right angles or 270⁰

∴ Fraction = 270⁰ / 360⁰

= 3 / 4

We know that one complete clockwise revolution, hour hand will rotate by 360⁰

(a) When hour hand of a clock starts at 12 and makes 1 / 2 revolution clockwise, it will rotate by 180⁰.

Hence, the hour hand of a clock will stop at 6.

(b) When hour hand of a clock starts at 2 and makes 1 / 2 revolution clockwise, it will rotate by 180⁰

Hence, the hour hand of a clock will stop at 8.

(c) When hour hand of a clock starts at 5 and makes 1 / 4 revolution clockwise, it will rotate by 90⁰

Hence, hour hand of a clock will stop at 8.

(d) When hour hand of a clock starts at 5 and makes 3 / 4 revolution clockwise, it will rotate by 270⁰

Hence, hour hand of a clock will stop at 2

Revolving one complete round in clockwise or in anti – clockwise direction we will revolve by 360⁰ and two adjacent directions are at 90⁰ or 1 / 4 of a complete revolution away from each other.

(a) If we start facing towards East and make 1 / 2 of a revolution clockwise, we will face towards West direction.

(b) If we start facing towards East and make 1 ½ of a revolution clockwise, we will face towards West direction

(c) If we start facing towards West and make 3 / 4 of a revolution anti – clockwise, we will face towards North direction

(d) If we start facing South and make one full revolution, again we will face the South direction.

In case of revolving 1 complete revolution, either clockwise or anti-clockwise we will be back at the original position.

By revolving one complete revolution either in clockwise or in anti-clockwise direction, we will revolve by 360⁰ and two adjacent directions are at 90⁰ or 1 / 4 of a complete revolution away from each other

(a) If we start facing towards East and turn clockwise to face North, we have to make 3 / 4 of a revolution

(b) If we start facing towards South and turn clockwise to face East, we have to make 3 / 4 of a revolution

(c) If we start facing towards West and turn clockwise to face East, we have to make 1 / 2 of a revolution

The hour hand of a clock revolves by 360⁰ or it covers 4 right angles in one complete revolution

(a) If hour hand of a clock goes from 3 to 6, it revolves by 90⁰ or 1 right angle

(b) If hour hand of a clock goes from 2 to 8, it revolves by 180⁰ or 2 right angles

(c) If hour hand of a clock goes from 5 to 11, it revolves by 180⁰ or 2 right angles

(d) If hour hand of a clock goes from 10 to 1, it revolves by 90⁰ or 1 right angle

(e) If hour hand of a clock goes from 12 to 9, it revolves by 270⁰ or 3 right angles

(f) If hour hand of a clock goes from 12 to 6, it revolves by 180⁰ or 2 right angles

By revolving one complete round in either clockwise or anti-clockwise direction, we will revolve by 360⁰ and two adjacent directions are at 90⁰ away from each other.

(a) If we start facing towards South and turn clockwise to West, we have to make one right angle

(b) If we start facing towards North and turn anti-clockwise to East, we have to make 3 right angles

(c) If we start facing towards West and turn to West, we have to make one complete round or 4 right angles

(d) If we start facing towards South and turn to North, we have to make 2 right angles

We know that in 1 complete revolution in either clockwise or anticlockwise direction, hour hand of a clock will rotate by 360⁰ or 4 right angles

(a) If hour hand of a clock starts from 6 and turns through 1 right angle, it will stop at 9

(b) If hour hand of a clock starts from 8 and turns through 2 right angles, it will stop at 2

(c) If hour hand of a clock starts from 10 and turns through 3 right angles, it will stop at 7

(d) If hour hand of a clock starts from 7 and turns through 2 straight angles, it will stop at 7