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 measure of two right angle 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 ……….. .

Measure and classify each angle:

From the following two angles, which has longer measure? Estimate and then confirm by measuring them.

Find the angle measure between the hands of the clock in each figure:

Investigate:

In the given figure, the angle measures 30°. Look at the same figure through a magnifying glass.

Does the angle become larger? Does the size of the angle change?

Find the measure of the angle shown in each figure. (First estimate with your eyes and then find the actual measure with a protractor.).

Which angle has a large measure? First estimate and then measure.

Measure of ∠A =

Measure of ∠B =

Write down the measures of

(a) some acute angles.

(b) some obtuse angles.

(Give two examples of each).

Say True or False:

(a) The measure of an acute angle < 90°.

(b) The measure of an obtuse angle < 90°.

(c) The measure of a reflex angle > 180°.

(d) The measure of one complete revolution = 360°

(e) If m∠A = 53° and m∠B = 35°, then m∠A > m∠B.

What is the measure of

(i) a right angle?

(ii) a straight angle?

Measure the angles given below, using the Protractor and write down the measure.