Learn › Class 9 CBSE · Mathematics › Triangles
Triangles — Class 9 CBSE Mathematics MCQs with Solutions
Free Class 9 CBSE Mathematics Triangles MCQs with step-by-step solutions. Practise online on Prepizo — no login needed.
▶ Practise Triangles online (free)
Sample questions with solutions
Q1 — easy
Two geometric triangles are congruent if they have:
A. Same shape only
B. Same size only
C. Same shape and same size ✓ Correct
D. Different area
Solution: Congruence implies identical shape and dimensions.
Q2 — easy
Which of the following is NOT a valid congruence criterion for triangles?
A. SAS
B. ASA
C. AAA ✓ Correct
D. RHS
Solution: AAA establishes similarity, not congruence.
Q3 — easy
In △ABC and △PQR, AB = PQ, BC = QR, and AC = PR. Criteria for congruence is:
A. SAS
B. SSS ✓ Correct
C. ASA
D. RHS
Solution: Three corresponding equal sides = SSS congruence.
Q4 — easy
In right-angled △ABC and △DEF, hypotenuse AC = DF and side AB = DE. Criteria is:
A. SAS
B. RHS ✓ Correct
C. SSS
D. ASA
Solution: Right-angle, Hypotenuse, Side = RHS criterion.
Q5 — easy
If △ABC ≅ △PQR, then side BC corresponds to side:
A. PQ
B. QR ✓ Correct
C. PR
D. AP
Solution: Corresponding parts of congruent triangles (CPCT): BC = QR.
Q6 — easy
In △ABC, if AB = AC and ∠B = 50°, then ∠C =
A. 50° ✓ Correct
B. 80°
C. 60°
D. 100°
Solution: Angles opposite to equal sides of an isosceles triangle are equal.
Q7 — easy
In △ABC, if ∠B = ∠C = 65°, then which sides are equal?
A. AB = BC
B. AB = AC ✓ Correct
C. BC = AC
D. None
Solution: Sides opposite to equal angles are equal: AB = AC.
Q8 — easy
In an isosceles right-angled triangle, measure of two acute angles is:
A. 30° and 60°
B. 45° and 45° ✓ Correct
C. 60° and 60°
D. 40° and 50°
Solution: 90° + x + x = 180° → 2x = 90° → x = 45°.
Q9 — easy
If △PQR ≅ △XYZ under correspondence PQR ↔ YXZ, then ∠Q =
A. ∠Y
B. ∠X ✓ Correct
C. ∠Z
D. ∠P
Solution: Second letter Q corresponds to second letter X → ∠Q = ∠X.
Q10 — easy
In △ABC, if ∠A = 40° and ∠B = 80°, longest side of triangle is:
A. AB
B. BC
C. AC ✓ Correct
D. Cannot determine
Solution: ∠C = 180° − 120° = 60°. Largest angle is ∠B (80°), so opposite side AC is longest.
Q11 — easy
In △ABC, if AB = 5 cm, BC = 6 cm, AC = 7 cm, largest angle is:
A. ∠A
B. ∠B ✓ Correct
C. ∠C
D. Equal
Solution: Side AC (7 cm) is longest, so opposite angle ∠B is largest.
Q12 — easy
Difference of any two sides of a triangle is always _______ than third side.
A. Greater
B. Smaller ✓ Correct
C. Equal
D. Double
Solution: |a − b| < c.
Q13 — easy
If △ABC is congruent to △FED under ABC ↔ FED, then side FC corresponds to:
A. AB
B. BC
C. AC ✓ Correct
D. DE
Solution: A corresponds to F, C corresponds to D → AC = FD.
Q14 — easy
Perpendicular drawn from vertex of an isosceles triangle to non-equal base:
A. Bisects the base and vertex angle ✓ Correct
B. Is parallel to base
C. Is equal to base
D. Lies outside triangle
Solution: Altitude to base in an isosceles triangle bisects base and vertex angle.
Q15 — medium
Each angle of an equilateral triangle measures:
A. 45°
B. 60° ✓ Correct
C. 90°
D. 30°
Solution: 180° ÷ 3 = 60°.