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Class 9 Mathematics 14 questions 30 marks 45 min
Triangles
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Class 9 · Mathematics · 10 Aug 2026

Class 9 · Mathematics · 14 questions · 30 marks

Q.1 MCQ [5 marks]
(a)

Which congruence criterion is NOT sufficient to prove that two triangles are congruent?

[1 mark]
(a) SAS
(b) ASA
(c) SSA
(d) SSS
(b)

The areas of two similar triangles are 81 cm² and 49 cm² respectively. If the altitude of the first triangle is 6.3 cm, find the corresponding altitude of the second triangle.

[2 marks]
(a) 4.9 cm
(b) 5.4 cm
(c) 7.0 cm
(d) 4.2 cm
(c)

Let \Delta ABC \sim \Delta PQR. If \frac{\text{Perimeter}(\Delta ABC)}{\text{Perimeter}(\Delta PQR)} = \frac{3}{5} and QR = 15 cm, what is the length of BC?

[2 marks]
(a) 9 cm
(b) 25 cm
(c) 12 cm
(d) 10 cm
Q.2 Match the Pairs [4 marks]
(a)

Match each type of triangle with its defining property regarding sides.

[2 marks]
Column AColumn B
1. Scalene triangle a. All three sides are of different lengths
2. Isosceles triangle b. Two sides are of equal length
3. Equilateral triangle c. All three sides are of equal length

Answer: __________________________________________

(b)

Match the term with its corresponding geometric property in triangle geometry.

[2 marks]
Column AColumn B
1. Equilateral Triangle a. All angles are 60 degrees
2. Right Triangle b. One angle is 90 degrees
3. Scalene Triangle c. All sides have different lengths
4. Obtuse Triangle d. One angle is greater than 90 degrees

Answer: __________________________________________

Q.3 Fill in the Blanks [4 marks]
(a)

In an isosceles triangle ABC where AB = AC, the angles opposite to the equal sides are _____, and the line segment from the vertex A perpendicular to BC bisects the _____.

[2 marks]
(b)

If the altitudes from two vertices of a triangle to the opposite sides are equal, then the triangle is an _____ triangle.

[2 marks]
Q.4 One Sentence [3 marks]
(a)

State the condition under which two triangles are congruent by the RHS (Right-angle Hypotenuse Side) criterion.

[2 marks]
(b)

Define the SSS congruence rule as it applies to two triangles in a geometric proof.

[1 mark]
Q.5 Short Answer [5 marks]
(a)

Define an exterior angle of a triangle and state its relationship with the interior opposite angles.

[2 marks]
(b)

In triangle PQR, angle P = 60 degrees and angle Q = 40 degrees. Determine the measure of angle R and state the theorem used.

[3 marks]
Q.6 Word Problem [7 marks]
(a)

Rohan is flying a kite in Jaipur during Makar Sankranti. The string of the kite is 100 m long and it makes an angle of 30° with the horizontal ground. Assuming there is no slack in the string, calculate the height of the kite above the ground.

[3 marks]
(b)

A ladder 10 meters long reaches a window 8 meters above the ground in a housing society in Mumbai. Keeping its foot at the same point, the ladder is turned to the other side of the street to reach a window 6 meters high. Find the width of the street.

[4 marks]
7.

Consider two similar triangles ABC and PQR where angle A = angle P and angle B = angle Q. Identify the correct corresponding proportional side relationship from the choices below.

[2 marks]
Label the following: 1. ___________________ 2. ___________________ 3. ___________________ 4. ___________________
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