Problem Set 2 Geometry 9th Std Maths Part 2 Answers Chapter 2 Parallel Lines
i. If a transversal intersects two parallel lines then the sum of interior angles on the same side of the transversal is ____.
(A) 0°
(B) 90°
(C) 180°
(D) 360°
(C) 180°
ii. The number of angles formed by a transversal of two lines is _____.
(A) 2
(B) 4
(C) 8
(D) 16
Answer:
(C) 8
iii. A transversal intersects two parallel lines. If the measure of one of the angles is 40°, then the measure of its corresponding angle is ______.
(A) 40°
(B) 140°
(C) 50°
(D) 180°
Answer:
(A) 40°
iv. In ∆ABC, ∠A = 76°, ∠B = 48°, then ∠C = _____.
(A) 66°
(B) 56°
(C) 124°
(D) 28°
Answer:
In ∆ABC, ∠A + ∠B + ∠C = 180°
∴ ∠C = 180° – 76° – 48° = 56°
(B) 56°
v. Two parallel lines are intersected by a transversal. If measure of one of the alternate interior angles is 75° then the measure of the other angle is _____.
(A) 105°
(B) 15°
(C) 75°
(D) 45°
Answer:
(C) 75°
Question 2
Maharashtra Board Solution
Ray PQ and ray PR are perpendicular to each other. Points B and A are in the interior and exterior of ∠QPR respectively. Ray PB and ray PA are perpendicular to each other. Draw a figure showing all these rays and write – i. A pair of complementary angles ii. A pair of supplementary angles iii. A pair of congruent angles.
Solution & Step-by-Step Answer:
i. Complementary angles: ∠RPQ = 90° [Ray PQ ⊥ ray PR] ∴ ∠RPB + ∠BPQ = 90° [Angle addition property] ∠RPB and ∠BPQ are pair of complementary angles ∠APB = 90° [Ray PA ⊥ ray PB] ∴ ∠APR + ∠RPB = 90° ∠APR and ∠RPB are pair of complementary angles.
ii. Supplementary angles: iii. Congruent angles:
Question 3
Maharashtra Board Solution
Prove that, if a line is perpendicular to one of the two parallel lines, then it is perpendicular to the other line also. Given: line AB || line CD and line EF intersects them at P and Q respectively. line EF ⊥ line AB To prove: line EF ⊥ line CD
Solution & Step-by-Step Answer:
Proof: line EF ⊥ line AB [Given] ∴ ∠APR = 90° ….(i) line AB || line CD and line EF is their transversal. ∴ ∠EPB ≅ ∠PQD …..(ii) [Corresponding angles] ∴ ∠PQD = 90° [From (i) and (ii)] ∴ line EF ⊥ line CD
Question 4
Maharashtra Board Solution
In the given figure, measures of some angles are shown. Using the measures find the measures of ∠x and ∠y and hence show that line l || line m.
Solution & Step-by-Step Answer:
Proof: ∠x = 130° ∠y = 50° [Vertically opposite angles] Here, m∠PQT + m∠QTS = 130° + 50° = 180° But, ∠ PQT and ∠ QTS are a pair of interior angles on lines l and m when line n is the transversal, ∴ line l || line m [Interior angles test]
Question 5
Maharashtra Board Solution
In the given figure, Line AB || line CD || line EF and line QP is their transversal. If y : z = 3 : 7 then find the measure of ∠x.
Solution & Step-by-Step Answer:
y : z = 3 : 7 [Given] Let the common multiple be m ∴ ∠j = 3m and ∠z = 7m ….(i) line AB || line EF and line PQ is their transversal [Given] ∠x = ∠z ∴ ∠x = 7m …..(ii) [From (i)] line AB || line CD and line PQ is their transversal [Given] ∠x + ∠y = 180° ∴ 7m + 3m = 180° ∴ 10m = 180° ∴ m = 18° ∴ ∠x = 7m = 7(18°) [From (ii)] ∴ ∠x = 126°
Question 6
Maharashtra Board Solution
In the given figure, if line q || line r, line p is their transversal and if a = 80°, find the values of f and g.
Solution & Step-by-Step Answer:
i. ∠a = 80° [Given] ∠g = ∠a [Alternate exterior angles] ∴ ∠g = 80° …..(i)
ii. Now, line q || line r and line p is their transversal.
Question 7
Maharashtra Board Solution
In the given figure, if line AB || line CF and line BC || line ED then prove that ∠ABC = ∠FDE. Given: line AB || line CF and line BC || line ED To prove: ∠ABC = ∠FDE
Solution & Step-by-Step Answer:
Proof: line AB || line PF and line BC is their transversal. ∴ ∠ABC = ∠BCD ….(i) [Alternate angles] line BC || line ED and line CD is their transversal. ∴ ∠BCD = ∠FDE ….(ii) [Corresponding angles] ∴ ∠ABC = ∠FDE [From (i) and (ii)]
Maharashtra Board Class 9 Maths Chapter 2 Parallel Lines Problem Set 2 Intext Questions and Activities
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