CBSE Class 10 Mathematics Triangles Assignment Set A

Multiple Choice Questions 

Question. If in two triangles ABC and PQR, AB/QR = BC/PR = CA/PQ, then
(a) ∆PQR ~ ∆CAB
(b) ∆PQR ~ ∆ABC
(c) ∆CBA ~ ∆PQR
(d) ∆BCA ~ ∆PQR
Answer : A

Question. The perimeters of two similar triangles ∆ABC and ∆PQR are 35 cm and 45 cm respectively, then the ratio of the areas of the two triangles is
(a) 7 : 9
(b) 28 : 45
(c) 14 : 27
(d) 49 : 81
Answer : D

Question. In the given figures, ∆PQR ∼ ∆XYZ. If PQ = 4 cm, QR = 5 cm and XY = 6 cm, then YZ equals.

(a) 4.5 cm
(b) 7.5 cm
(c) 6.4 cm
(d) None of these
Answer : B

Question. Corresponding sides of two similar triangles are in the ratio 9 : 5. Areas of these triangles are in the ratio
(a) 21 : 85
(b) 81 : 25
(c) 9 : 5
(d) 5 : 9
Answer : B

Question. In the given figure, DE || BC, AD = 1 cm and BD = 2 cm. What is the ratio of the ar (∆ABC) to the ar (∆ADE)?

(a) 1 : 9
(b) 1 : 7
(c) 9 : 1
(d) 7 : 1
Answer : C

Question. The sides of two similar triangles are in the ratio 2 : 3, then the areas of these triangles are in the ratio
(a) 2 : 5
(b) 4 : 9
(c) 7 : 16
(d) None of these
Answer : B

Question. If ∆PQR ~ ∆XYZ, ∠Q = 50° and ∠R = 70°, then ∠X + ∠Y is equal to
(a) 70°
(b) 110°
(c) 120°
(d) 50°
Answer : B

Question. Given ∆ABC ~ ∆PQR, if AB/PQ = 1/3, then ar(∆ABC)/ar(∆PQR) =
(a) 1 : 3
(b) 1 : 6
(c) 1 : 9
(d) 1 : 5
Answer : C

Question. ∆ABC is isosceles with AC = BC. If AB² = 2AC², then the measure of ∠C is
(a) 30°
(b) 60°
(c) 45°
(d) 90°
Answer : D

Question. The perimeters of two similar triangles are 25 cm and 15 cm respectively. If one side of the first triangle is 9 cm, then the corresponding side of second triangle is
(a) 5.4 cm
(b) 8 cm
(c) 9.5 cm
(d) 10 cm
Answer : A

Question. Let ∆ABC ∼ ∆DEF, ar (∆ABC) = 169 cm² and ar (∆DEF) = 121 cm². If AB = 26 cm, then DE equals
(a) 11 cm
(b) 22 cm
(c) 33 cm
(d) 44 cm
Answer : B

Question. In the given figure, M is mid-point of side CD of a parallelogram ABCD. The line BM is drawn intersecting AC at L and AD produced at E. Then EL =

(a) BL
(b) (1/2) BL
(c) 2BL
(d) None of these
Answer : C

Question. In a trapezium ABCD, AC and BD intersecting at O, AB || DC and AB = 2CD, if area of ∆AOB = 84 cm², the area of ∆COD is
(a) 12 cm²
(b) 18 cm²
(c) 21 cm²
(d) 27 cm²
Answer : C

Question. In the given figure, DEFG is a square and ∠BAC = 90°. Then FG² =

(a) BG × FC
(b) BG + FC
(c) BG/FC
(d) None of these
Answer : A

Assertion-Reason Type Questions

In the following questions, a statement of assertion (A) is followed by a statement of reason (R). Choose 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.

Question. Assertion (A): In the given figures, ∆ABC ~ ∆GHI.
Reason (R): If the corresponding sides of two triangles are proportional, then they are similar.
Answer : A

Question. Assertion (A): The sides of two similar triangles are in the ratio 2 : 5, then the areas of these triangles are in the ratio 4 : 25.
Reason (R): The ratio of the areas of two similar triangles is equal to the square of the ratio of their sides.
Answer : A

Level-1

Fill in the blanks:

1. All ……………………triangles are similar. (Equilateral)

2. If a line divides two sides of a triangle in the same ratio, the line is ..........................to the third side. (Parallel)

3. Sides of two similar triangles are in the ratio 4:9.The ratio of areas of these triangles is ……………. (16:81)

4. Two triangle are said to be similar if................ (Corresponding sides are in same ratio and corresponding angles are equal)

5. Triangle have ........diagonals. (No)

6. The six elements of a triangle are its three angles and the ------------------- (three sides)

Level-2

7. Find the length of x in the following cases:

8. A Ladder 25m long reaches a window of a building 20m above the ground. Determine the distance of the foot of the ladder from the building.

Please click the link below to download CBSE Class 10 Mathematics Triangles Assignment Set A