Practice the problems of Math in Focus Grade 4 Workbook Answer Key Chapter 9 Angles to score better marks in the exam.

Math Journal

Question 1.

a. Two right angles form a $$\frac{1}{2}$$-turn.
Yes.

Explanation:
Yes, two right angles form a $$\frac{1}{2}$$-turn.

b. The measure of an angle is a fraction of a $$\frac{3}{4}$$-turn.

c. An acute angle has a measure greater than 90°.
Wrong.

Explanation:
No, because the acute angle will be less than 90°. So the statement is wrong.

d. A $$\frac{1}{4}$$-turn is 90°.
Yes.

Explanation:
Yes, a $$\frac{1}{4}$$-turn is 90°.

e. A straight angle has a measure of 180°.
Yes.

Explanation:
Yes, a straight angle has a measure of 180°.

f. 150° is between a $$\frac{1}{4}$$ -turn and a $$\frac{1}{2}$$-turn.
Yes.

Explanation:
Yes, 150° is between a $$\frac{1}{4}$$ -turn and a $$\frac{1}{2}$$-turn.

Complete.

Question 2.

The names of the angle are ∠EFG, ∠FGE, and ∠F.
Wrong.

Explanation:
The names of the angle ∠FGE, and ∠F are wrong because the middle point must be a vertex.

Challenging Practice

Look at the clock. The hour hand and minute hand were at the position as shown in figure A. Figure B shows the position of the hour hand and minute hand after some time.

What fraction of a turn did the minute hand move? Explain your answer.

The fraction will be $$\frac{1}{4}$$.

Explanation:
Here, the fraction of a turn did the minute hand move is $$\frac{1}{4}$$.

Tom walks from J to K and at that point makes a $$\frac{1}{4}$$-turn to his right.
Then, he walks to H and at that point, makes a $$\frac{1}{2}$$-turn before walking on to the end of that line.
Here, Tom walks from J to K and at that point makes a $$\frac{1}{4}$$-turn to his right which is 90°, and then he walks to H, and at that point, makes a $$\frac{1}{2}$$-turn which is 180° before walking on to the end of that line. So he will be at point G.