This set of Mathematics Multiple Choice Questions & Answers (MCQs) focuses on “Lines and Angles Definitions and Basic Terms”.

1. A line with two endpoints is called __________

a) line

b) ray

c) line-segment

d) triangle

View Answer

Explanation: A line-segment has two endpoints, P and Q as shown in below diagram.

2. How many endpoints does a ray have?

a) One

b) Two

c) Three

d) Four

View Answer

Explanation: A ray has one end point P as shown in below diagram. It originates from this point.

3. If x is an acute angle, then what is true for x?

a) x = 90°

b) 0° < x < 90°

c) 90° < x < 180°

d) 180° < x < 360°

View Answer

Explanation: An acute angle always measures between 0° and 90°, therefore the value of an acute angle is always between 0° and 90°. It is shown in the diagram below in which ∠POQ is an acute angle whose value is less than 90°.

4. If x is an obtuse angle, then what is true for x?

a) x = 90°

b) 180° < x < 360°

c) 0° < x < 90°

d) 90° < x < 180°

View Answer

Explanation: An obtuse angle always measures between 90° and 180°, therefore the value of an acute angle is always between 90° and 180°. In the diagram given below, ∠PQR is an obtuse angle whose value is greater than 90° and less than 180°.

5. If x is a right angle, what is true for x?

a) x = 90°

b) 180° < x < 360°

c) 0° < x < 90°

d) 90° < x < 180°

View Answer

Explanation: A right angle is exactly equal to 90°. It is shown in the diagram below in which ∠POQ is the right angle whose value is equal to 90°.

6. What is the angle formed by a line?

a) 90°

b) 180°

c) 270°

d) 360°

View Answer

Explanation: It can be shown in the diagram given below that angle formed by a line is 180 degree.

7. If 180° < x < 360°, then x is a __________ angle.

a) acute

b) obtuse

c) reflex

d) right

View Answer

Explanation: An angle which is greater than 180° but less than 360° is called reflex angle. It is shown in the diagram below in which ∠PQR is a reflex angle.

8. From the given diagram below, which are the pairs of adjacent angles?

a) ∠PQR and ∠PQS

b) ∠PQR and ∠SQR

c) ∠PQR and ∠RQP

d) ∠PQS and ∠SQR

View Answer

Explanation: ∠PQS and ∠SQR are adjacent angles because they have one common arm (ray QS) and one common vertex (Point Q), ray PQ and ray QR are their non-common arms.

For adjacent angles ∠PQS and ∠SQR,

∠PQS + ∠SQR = ∠PQR.

9. From the given diagram below, which pair do angles POR and ROQ form?

a) Linear

b) Adjacent

c) Vertically opposite

d) Supplementary

View Answer

Explanation: Linear pair of angles is formed when non-common arms of two angles form a line.

In the given diagram, non-common arms of two angles POR and ROQ are OP and OQ form a line PQ.

10. The sum of complimentary angles is __________

a) > 90°

b) < 90°

c) = 90°

d) = 180°

View Answer

Explanation: When the sum of two angles are equal to 90°, they are called complimentary angles. In the diagram shown below, ∠POR and ∠ROQ are complimentary angles because ∠POR + ∠ROQ = 90°.

11. The sum of two supplementary angles is __________

a) > 90°

b) < 90°

c) = 90°

d) = 180°

View Answer

Explanation: When the sum of two angles are equal to 180°, they are called supplementary angles. In the diagram shown below, ∠POR and ∠ROQ are supplementary angles because ∠POR + ∠ROQ = 180°.

**Sanfoundry Global Education & Learning Series – Mathematics – Class 9**.

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