Exercise 5.2
Write ‘True’ or ‘False’. Correct all those that are false.
An angle smaller than a right angle is an acute angle.
A right angle measures 180°.
A straight angle measures 90°.
The measure greater than 180° is a reflex angle.
A complete angle measures 360°.
True
False
Which angles in the adjacent figure are acute and which are obtuse ? Check your estimation by measuring them. Write their measures too.
Answer:
∠1, ∠3
∠2, ∠4
100°
80°
Obtuse Angle
Acute Angle
What is the measure of these angles? Which is the largest angle? Draw an angle larger than the largest angle.
Answer: ∠
Now, draw an angle larger than that!
Write the type of angle formed between the long hand and short hand of a clock at the given timings. (Take the small hand as the base)
(i) At 9’0 clock in the morning
(ii) At 6’0 clock in the evening
(iii) At 12 noon
(iv) At 4’0 clock in the afternoon
(v) At 8’0 clock in the night.
9:00 a.m.
12:00 noon
8:00 p.m.
6:00 p.m.
4:00 p.m.
Zero Angle
Right Angle
Obtuse Angle
Straight Angle
5. Match the angles by measure. Draw figures for these as well.
270°
45°
180°
90°
150°
Acute angle
Right angle
Obtuse angle
Reflex angle
Straight angle