# Mathematics Questions and Answers – Lines and Angles Definitions and Basic Terms

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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

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

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°

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°

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°

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°

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

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

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
c) Vertically opposite
d) Supplementary

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°

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°  