Exercise 5.4
1. What is the measure of
(i) a right angle?
(ii) a straight angle? (Write in form of degrees) ?
2. Say True or False :
3. Write down the measures of.(give at least two examples of each)
(a) some acute angles (Hint : > 90 degrees) :
(b) some obtuse angles (Hint : < 90 degrees) :
4. Measure the angles given below using the Protractor and write down the measure.
a.
b.
c.
d. ∠1 =
- Which angle has a large measure?First estimate and then measure.
Measure of Angle A =
Measure of Angle B =
6. From these two angles which has larger measure? Estimate and then confirm by measuring them.
: ∠A =
: ∠B
7. Fill in the blanks with acute, obtuse, right or straight.
(a) An angle whose measure is less than that of a right angle is
(b) An angle whose measure is greater than that of a right angle is
(c) An angle whose measure is the sum of the measures of two right angles is
(d) When the sum of the measures of two angles is that of a right angle, then each one of them is
(e) When the sum of the measures of two angles is that of a straight angle and if one of them is acute then the other should be
8. Find the measure of the angle shown in each figure. (First estimate with your eyes and then find the actual measure with a protractor).
a.
b.
c.
d.
9. Find the angle measure between the hands of the clock in each figure ?
a. At 9.00 am :
b. At 1.00 pm :
c. At 6.00 pm :
10. Investigate: In the given figure, the angle measures 30°. Look at the same figure through a magnifying glass.Does the angle becomes larger? Does the size of the angle change?
Solution:
The angle doesn't change, the rays would change their length, hence the size of angle increases.
11. Measure and classify each angle ?
| Angle | Measure | Type |
|---|---|---|
| ∠AOB | ||
| ∠AOC | ||
| ∠BOC | ||
| ∠DOC | ||
| ∠DOA | ||
| ∠DOB |