CBSE Class 7 Mathematics A Tale of Three Intersecting Lines MCQs Set 10

Question. Given angles 90° and 85°, can they be angles of a triangle?
(a) No, because 90° + 85° < 180°
(b) No, because 90° is a right angle
(c) Yes, because 90° + 85° is less than 180°
(d) Yes, if the third angle is 5°

Answer: C

Question. Given angles 50° and 150°, can they be angles of a triangle?
(a) Yes
(b) Only if the side is short
(c) No, because 50° + 150° is greater than 180°
(d) Yes, if the third angle is 20°

Answer: C

Question. What is an exterior angle of a triangle?
(a) The angle between two sides inside the triangle
(b) The angle formed by extending one side and the adjacent side
(c) The angle at the vertex of the triangle
(d) The angle formed by two altitudes

Answer: B

Question. If the sum of two given angles is less than 180°, what can we say about the possibility of triangle existence?
(a) A triangle is not possible
(b) A triangle might exist
(c) A triangle exists with these angles
(d) We need the side length to decide

Answer: C

Question. If two angles are 60° and 70°, the sum is 130°. Does changing the length of the included side change the third angle measure?
(a) Yes, the third angle changes
(b) Yes, the third angle increases
(c) No, the third angle remains the same
(d) Only if the change is very big

Answer: C

Question. If ∠ B = 50° and ∠ C = 70° in △ABC, we can find ∠ A without construction by knowing that the sum of all three angles is what?
(a) 90°
(b) 360°
(c) 180°
(d) 120°

Answer: C

Question. If ?A = 50° and ?B = 60° in a triangle, what is the measure of the exterior angle at vertex C?
(a) 90°
(b) 100°
(c) 110°
(d) 120°

Answer: C

Question. In the proof of Angle Sum Property, we draw a line XY parallel to the base BC through vertex A. Why do we do this step?
(a) To measure the angles easily
(b) To prove that BC is the shortest side
(c) To relate the angles ∠ B and ∠ C to the angles at vertex A (on the straight line XY)
(d) To make the triangle look equilateral

Answer: C

Question. Since XY is parallel to BC, ∠ XAB is equal to ∠ B and ∠ YAC is equal to ∠ C. This is due to what angle relationship?
(a) Corresponding angles
(b) Interior angles
(c) Alternate angles
(d) Adjacent angles

Answer: C

Question. Since ∠ XAB + \angle BAC + \angle YAC form a straight angle on line XY, their sum is how much?
(a) 90°
(b) 360°
(c) 180°
(d) 270°

Answer: C

Question. If ∠ B = 50° and ∠ C = 70°, then ∠ BAC is 180° - (50° + 70°). What is the measure of ∠ BAC?
(a) 50°
(b) 70°
(c) 60°
(d) 120°

Answer: C

Question. If two angles are 36° and 72°, what must be the third angle measure?
(a) 108°
(b) 36°
(c) 72°
(d) 62°

Answer: C

Question. If two angles are 150° and 15°, what must be the third angle measure?
(a) 25°
(b) 15°
(c) 15°
(d) 30°

Answer: C

Question. If all the angles in a triangle are equal, then the triangle is equilateral. What is the measure of each angle?
(a) 90°
(b) 180°
(c) 60°
(d) 45°

Answer: C

Question. What is the altitude of a triangle?
(a) A line segment connecting two vertices
(b) A perpendicular line segment from a vertex to the opposite side
(c) A line segment bisecting an angle
(d) A line segment parallel to the base

Answer: B

Question. In an isosceles triangle △ABC, if ∠ A = 50° and ∠ B = \angle C, how much is ∠ B?
(a) 50°
(b) 130°
(c) 65°
(d) 90°

Answer: C

Question. The statement that the sum of the three angles in any triangle is 180° is called the what?
(a) Triangle Inequality
(b) Parallel Postulate
(c) Angle Sum Property of triangles
(d) Straight Angle Rule

Answer: C

Question. The folding of a paper triangle showing that the three angles meet on a straight line is a way of what?
(a) Constructing the median
(b) Proving the triangle inequality
(c) Verifying the angle sum property
(d) Finding the altitude

Answer: C

Question. The angle ∠ ACD formed between the extension of side BC and side AC is called the what?
(a) Interior angle
(b) Opposite angle
(c) Exterior angle
(d) Right angle

Answer: C

Question. If ∠ A = 50° and ∠ B = 60° in △ABC, the adjacent interior angle ∠ ACB is 70°. What is the measure of the exterior angle ∠ ACD?
(a) 70°
(b) 180°
(c) 110°
(d) 130°

Answer: C