Exercise 5.3
1. Match the following:
(i) Straight angle ↔ (c) Half of a revolution
(ii) Right angle ↔ (d) One-fourth of a revolution
(iii) Acute angle ↔ (a) Less than one-fourth of a revolution
(iv) Obtuse angle ↔ (e) Between \(\frac{1}{4}\) and \(\frac{1}{2}\) of a revolution
(v) Reflex angle ↔ (b) More than half a revolution
(ii) Right angle ↔ (d) One-fourth of a revolution
(iii) Acute angle ↔ (a) Less than one-fourth of a revolution
(iv) Obtuse angle ↔ (e) Between \(\frac{1}{4}\) and \(\frac{1}{2}\) of a revolution
(v) Reflex angle ↔ (b) More than half a revolution
Correct Matches: (i)-c, (ii)-d, (iii)-a, (iv)-e, (v)-b
2. Classify each one of the following angles as right, straight, acute, obtuse or reflex:
(a)
The angle is less than 90°.
∴ It is an Acute angle.
∴ It is an Acute angle.
(b)
The angle is greater than 90° but less than 180°.
∴ It is an Obtuse angle.
∴ It is an Obtuse angle.
(c)
The angle forms a perfect corner (90°).
∴ It is a Right angle.
∴ It is a Right angle.
(d)
The angle is greater than 180° but less than 360°.
∴ It is a Reflex angle.
∴ It is a Reflex angle.
(e)
The angle forms a straight line (180°).
∴ It is a Straight angle.
∴ It is a Straight angle.
(f)
The angles are smaller than 90°.
∴ They are Acute angles.
∴ They are Acute angles.
(a) Acute (b) Obtuse (c) Right (d) Reflex (e) Straight (f) Acute