Assertion and Reason Questions for Class 9 Maths Chapter 6 Lines and Angles
Directions: In the following questions, a statement of assertion (A) is followed by a statement of reason (R). Mark the correct choice as:
(a) Both assertion (A) and reason (R) are true and reason (R) is the correct explanation of assertion (A).
(b) Both assertion (A) and reason (R) are true but reason (R) is not the correct explanation of assertion (A).
(C) Assertion (A) is true but reason (R) is false.
(d) Assertion (A) is false but reason (R) is true.
Q.1. Assertion : Sum of the pair of angles 120° and 60° is supplementary.
Reason: Two angles, the sum of whose measures is 180°, are called supplementary angles.
Answer
Answer: (a)Q.2. Assertion: The angles of a triangle are in the ratio 2:3: 4. The largest angle of the triangle is 80°.
Reason: The sum of all the interior angles of a triangle is 180°
Answer
Answer: (a)Q.3. Assertion : If angles ‘a’ and ‘b’ form a linear pair of angles and a = 40°, then b = 150°.
Reason: Sum of linear pair of angles is always 180°.
Answer
Answer: (d)Q.4. Assertion: In the given figure, AOB is a straight line. If ∠AOC = (3x + 10)° and ∠BOC (4x – 26)°, then ∠BOC = 860
Reason: The sum of angles that are formed on a straight line is equal to 180°
Answer
Answer: (a)Q.5. Assertion : If two interior angles on the same side of a transversal intersecting two parallel lines are in the ratio 5:4, then the greater of the two angles is 1000
Reason: If a transversal intersects two parallel lines, then the sum of the interior angles on the same side of the transversal is 1800
Answer
Answer: (a)Q.6. Assertion : An angle is 14º more than its complementary angle, then angle is 52º.
Reason: Two angles are said to be supplementary if their sum of measure of angles is 180°
Answer
Answer: (b)Q.7. Assertion : Supplement of angle is one fourth of itself. The measure of the angle is 1440
Reason: Two angles are said to be supplementary if their sum of measure of angles is 1800
Answer
Answer: (a)Q.8. Assertion: The value of x from the adjoining figure, if ℓ || m is 15º.
Reason: If two parallel lines are intersected by a transversal, then each pair of corresponding angles so formed is equal.
Answer
Answer: (b)Q.9. Assertion : If two internal opposite angles of a triangle are equal and external angle is given to be 110°, then each of the equal internal angle is 550.
Reason: A triangle with one of its angle 900, is called a right triangle
Answer
Answer: (b)Q.10. Assertion : A triangle can have two obtuse angles.
Reason: The sum of all the interior angles of a triangle is 180°
Answer
Answer: (d)Q.11. Assertion : The angles of a triangle are in the ration 3:5:7. The triangle is acute-angled
Reason: The sum of angles that are formed on a straight line is equal to 180°.
Answer
Answer: (b)Frequently Asked Questions (FAQs)
A line segment is a part of a line with two end-points.
When two lines cut each other at right angle, then lines are called perpendicular lines.Â
Two lines are said to be parallel when they do not meet at any point or which do not intersects each other.
When a line intersects two lines at distinct points, it is called a transversal.
Collinear points are a set of points (3 or more) which lie on the same line.
A ray is a part of a line, which has a starting point and extends infinitely in one direction.
If the inclination between the arms is less than a right angle, it is called an acute angle.
If the inclination between the arms is more than a right angle, it is called an obtuse angle.
If the arms form an angle of 90 degrees between them, it is called a right angle.
Two angles whose sum is equal to 90 degrees are called complementary angles.
Two angles whose sum is equal to 180 degrees are called supplementary angles.
Two angles which have a common side and a common vertex are called adjacent angles.
Two angles which are formed, opposite to each other, when two lines intersect at a point or vertex, are called vertically opposite angles.
