Question 1:
Match the following.
| Measure of the angle | Type of angle | ||
| (1) | 180° | (a) | Zero angle |
| (2) | 240° | (b) | Straight angle |
| (3) | 360° | (c) | Reflex angle |
| (4) | 0° | (d) | Complete angle |
ANSWER:
| Measure of the angle | Type of angle | ||
| (1) | 180° | (b) | Straight angle |
| (2) | 240° | (c) | Reflex angle |
| (3) | 360° | (d) | Complete angle |
| (4) | 0° | (a) | Zero angle |
Question 2:
The measures of some angles are given below. Write the type of each angle.
| (1) | 75° | (2) | 0° |
| (3) | 215° | (4) | 360° |
| (5) | 180° | (6) | 120° |
| (7) | 148° | (8) | 90° |
ANSWER:
(i) An angle whose measure is less than 90∘ is an acute angle.
(ii) An angle whose measure is 0∘ is a zero angle.
(iii) An angle whose measure is bigger than 180∘ but less than 360∘ is a reflex angle.
(iv) An angle whose measure is 360∘ is a complete angle.
(v) An angle whose measure is 180∘ is a straight angle.
(vi) An angle whose measure is bigger than 90∘ but less than 180∘ is an obtuse angle.
(vii) An angle whose measure is bigger than 90∘ but less than 180∘ is an obtuse angle.
(viii) An angle whose measure is 90∘ is a right angle.
(ii) An angle whose measure is 0∘ is a zero angle.
(iii) An angle whose measure is bigger than 180∘ but less than 360∘ is a reflex angle.
(iv) An angle whose measure is 360∘ is a complete angle.
(v) An angle whose measure is 180∘ is a straight angle.
(vi) An angle whose measure is bigger than 90∘ but less than 180∘ is an obtuse angle.
(vii) An angle whose measure is bigger than 90∘ but less than 180∘ is an obtuse angle.
(viii) An angle whose measure is 90∘ is a right angle.
Question 3:
Look at the figures below and write the type of each of the angles.
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ANSWER:
(a) An angle whose measure is less than 90∘ is an acute angle.
(b) An angle whose measure is 90∘ is a right angle.
(c) An angle whose measure is bigger than 180∘ but less than 360∘ is a reflex angle.
(d) An angle whose measure is 180∘ is a straight angle.
(e) An angle whose measure is 0∘ is a zero angle
(f) An angle whose measure is 360∘ is a complete angle.
(b) An angle whose measure is 90∘ is a right angle.
(c) An angle whose measure is bigger than 180∘ but less than 360∘ is a reflex angle.
(d) An angle whose measure is 180∘ is a straight angle.
(e) An angle whose measure is 0∘ is a zero angle
(f) An angle whose measure is 360∘ is a complete angle.
Question 4:
Use a protractor to draw an acute angle, a right angle and an obtuse angle.
ANSWER:
Question 1:
Use the proper geometrical instruments of construct the following angles. Use the compass and the ruler to bisect them.
(1) 50°
(1) 50°
ANSWER:
Steps of Constructions:
(1) Draw an angle ∠ABC of measure 50°.
(2) Now place the point of a compass on point B and with any convenient distance draw an arc to cut rays BA and BC. Name the points of intersection as P and Q respectively.
(3) Now, place the point of the compass at P and taking a convenient distance, draw an arc inside the angle. Using the same distance, draw another arc inside the angle from the point Q, to cut the previous arc.
(4) Name the point of intersection as point O. Now draw ray BO. Ray BO is the bisector of ∠ABC.
Question 2:
Use the proper geometrical instruments of construct the following angles. Use the compass and the ruler to bisect them.
(2) 115°
(2) 115°
ANSWER:
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Steps of Constructions:
(1) Draw an angle ∠ABC of measure 115°.
(2) Now place the point of a compass on point B and with any convenient distance draw an arc to cut rays BA and BC. Name the points of intersection as P and Q respectively.
(3) Now, place the point of the compass at P and taking a convenient distance, draw an arc inside the angle. Using the same distance, draw another arc inside the angle from the point Q, to cut the previous arc.
(4) Name the point of intersection as point O. Now draw ray BO. Ray BO is the bisector of ∠ABC.
Question 3:
Use the proper geometrical instruments of construct the following angles. Use the compass and the ruler to bisect them.
(3) 80°
(3) 80°
ANSWER:
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Steps of Constructions:
(1) Draw an angle ∠ABC of measure 80°.
(2) Now place the point of a compass on point B and with any convenient distance draw an arc to cut rays BA and BC. Name the points of intersection as P and Q respectively.
(3) Now, place the point of the compass at P and taking a convenient distance, draw an arc inside the angle. Using the same distance, draw another arc inside the angle from the point Q, to cut the previous arc.
(4) Name the point of intersection as point O. Now draw ray BO. Ray BO is the bisector of ∠ABC.
Question 4:
Use the proper geometrical instruments of construct the following angles. Use the compass and the ruler to bisect them.
(4) 90°
(4) 90°
ANSWER:
Steps of Constructions:
(1) Draw an angle ∠ABC of measure 90°.
(2) Now place the point of a compass on point B and with any convenient distance draw an arc to cut rays BA and BC. Name the points of intersection as P and Q respectively.
(3) Now, place the point of the compass at P and taking a convenient distance, draw an arc inside the angle. Using the same distance, draw another arc inside the angle from the point Q, to cut the previous arc.
(4) Name the point of intersection as point O. Now draw ray BO. Ray BO is the bisector of ∠ABC.
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