Acute, Obtuse and Reflex Angles

Q.

How many degrees does a minute hand of a clock turn through in one hour?

1. ${180}^{\circ }$

2. ${270}^{\circ }$

3. ${360}^{\circ }$

4. ${90}^{\circ }$

Q. Write the type of angle formed between the long hand and short hand of a clock at 4 o'clock in the afternoon?

1. Acute angle
2. Right angle
3. Obtuse angle
4. Straight angle

Q. When a clock is showing time as 9:00, the angle included between the hour and the minute hand is called ___.

1. right angle
2. straight angle
3. zero angle
4. acute angle

Q. ${270}^{\circ }$ is an example of angle.

1. reflex
2. obtuse
3. acute
4. straight

Q.

Question 74

Can we have two acute angles whose sum is

a) an acute angle? Why or Why not?

b) a right angle? Why or Why not?

c) an obtuse angle? Why or Why not?

d) a straight angle? Why or Why not?

e) a reflex angle? Why or Why not?

Q. The instrument used to measure an angle is called ____.

1. protractor
2. compass
3. divider
4. scale

Q. An angle of measure 360° is called

(a) a zero angle
(b) a straight angle
(c) a reflex angle
(d) a complete angle

Q. Arrange the type of angles according to their degree in ascending order from top to bottom.

1. Obtuse angle
2. Straight angle
3. Acute angle
4. Right angle
5. Reflex angle

Q.

Question 59

In the given figure,

a) Name any four angles that appear to be acute angles.

b) Name any two angles that appear to be obtuse angles.

Q.

Question 2 (a)

Say True or False:

The measure of an acute angle $<{90}^{\circ }$

Q.

Question 2 (b)

Say True or False:

The measure of an obtuse angle $<{90}^{\circ }$

Q.

Question 7 (a)

Where will the hour hand of a clock stop if it starts:
from 6 and turns through 1 right angle?

Q.

Question 11
If the sum of two angles is greater than ${180}^{\circ }$, then which of the following is not possible for the two angles?
a) One obtuse angle and one acute angle
b) One reflex angle and one acute angle
c) Two obtuse angles
d) Two right angles

Q.

Draw an angle of 70°. Make a copy of it using only a straight edge and compasses.

Q.

Question 75

Can we have two obtuse angles whose sum is

a) A reflex angle? Why or Why not?

b) A complete angle? Why or Why not?

Q.

What fraction of a clockwise revolution does the hour hand of a clock turn through, when it goes from,

$1\mathrm{to}10$

Q.

An angle larger than a straight angle is a ________ angle.

Q.

Question 1

Match the following:

(i) Straight angle (a) less than one-fourth a revolution
(ii) Right angle (b) more than half a revolution
(iii) Acute angle (c) half of a revolution
(iv) Obtuse angle (d) one-fourth a revolution
(v) Reflex angle (e) between $\frac{1}{4}$ and $\frac{1}{2}$ of a revolution
(f) One complete revolution

Q.

Question 10

Investigate: In the given figure, the angle measure ${30}^{\circ }$. Look at the same figure through a magnifying glass. Does the angle become larger? Does the size of the angle change?

Q.

Question 12
If the sum of two angles is equal to an obtuse angle, then which of the following is not possible?
a) One obtuse angle and one acute angle
b) One right angle and one acute angle
c) Two acute angles
d) Two right angles

Q.

What fraction of a clockwise revolution does the hour hand of a clock turn through, when it goes from,

$\left(\mathrm{a}\right)3\mathrm{to}9$

Q. Use the proper geometrical instruments of construct the following angles. Use the compass and the ruler to bisect them.
(1) 50°

Q.

Question 7 (a)

Fill in the blanks with acute, obtuse, right or straight:

An angle whose measure is less than that of a right angle is ____.

Q.

Question 2 (a)

Classify each one of the following angles as right, straight, acute, obtuse or reflex:

Q.

Question 2 (c)

Say True or False:

The measure of a reflex angle $>{180}^{\circ }$

Q.

Question 22

Fill in the blanks to make the statements true.

In the given figure,

a) $\angle AOD$ is a/an______angle.

b) $\angle COA$ is a/an______angle.

c) $\angle AOE$ is a/an______angle.

Q. Use the proper geometrical instruments of construct the following angles. Use the compass and the ruler to bisect them.
(4) 90°

Q.

Question 2 (b)

Classify each one of the following angles as right, straight, acute, obtuse or reflex:

Q.

How many degrees are there in one-third of a right angle?

Q.

Question 53

Draw two acute angles and one obtuse angle without using a protractor. Estimate the measures of the angles. Measure them with the help of a protractor and see how much accurate is your estimate?