Assertion And Reason Questions For Class 10 Maths Chapter 6 Triangles

Assertion And Reason Questions for Class 10 Maths Chapter 6 Triangles are available in this Maths article. Assertion And Reason Questions for Class 10 Maths Chapter 6 Triangles are very useful to solve the problems easily. This article helps the students to know the key questions and answers about Triangles. Triangles cover congruence, similarity, Pythagoras theorem, and area relationships, which we use in everyday calculations. Our subject experts have provided detailed solutions for these problems based on the CBSE syllabus and the NCERT textbook. This material helps students revise the chapter easily and perform well in the final examination. A free downloadable PDF is also available for easy practice and revision.

Important Assertion And Reason Questions on Triangles

Directions: In the following questions a statement of assertion (A) is followed by a statement of reason(R). Mark the correct choice as:

Choose the correct option for the following questions:

  • (A). Both Assertion (A) and Reason (R) are true, and Reason is the correct explanation of Assertion.

  • (B). Both Assertion (A) and Reason (R) are true, but Reason is not the correct explanation of Assertion.

  • (C). Assertion (A) is true, but Reason (R) is false.

  • (D). Assertion (A) is false, but Reason (R) is true.

Question 1:

Assertion (A): If two triangles are similar, their corresponding angles are equal.

Reason (R): In similar triangles, corresponding sides are proportional.

Options:

(A). Both A and R are true, and R is the correct explanation of A.
(B). Both A and R are true, but R is not the correct explanation of A.
(C). A is true, but R is false.
(D). A is false, but R is true.

Correct Answer: (B). Both A and R are true, but R is not the correct explanation of A.

Question 2: 

Assertion (A): Two equilateral triangles are always similar.

Reason (R): All angles of an equilateral triangle are (60^\circ).

Options:

(A). Both A and R are true, and R is the correct explanation of A.
(B). Both A and R are true, but R is not the correct explanation of A.
(C). A is true, but R is false.
(D). A is false, but R is true.

Correct Answer: (A). Both A and R are true, and R is the correct explanation of A.

Question 3:

Assertion (A): If two angles of one triangle are equal to two angles of another triangle, then the triangles are similar.

Reason (R): The third angles of the triangles will also be equal.

Options:

(A). Both A and R are true, and R is the correct explanation of A.
(B). Both A and R are true, but R is not the correct explanation of A.
(C). A is true, but R is false.
(D). A is false, but R is true.

Correct Answer: (A). Both A and R are true, and R is the correct explanation of A.

Question 4:

Assertion (A): The ratio of the areas of two similar triangles is equal to the square of the ratio of their corresponding sides.

Reason (R): Areas of similar figures depend on the square of the scale factor.

Options:

(A). Both A and R are true, and R is the correct explanation of A.
(B). Both A and R are true, but R is not the correct explanation of A.
(C). A is true, but R is false.
(D). A is false, but R is true.

Correct Answer: (A). Both A and R are true, and R is the correct explanation of A.

Question 5:

Assertion (A): If a line is drawn parallel to one side of a triangle, it divides the other two sides proportionally.

Reason (R): This is stated by the Basic Proportionality Theorem (BPT).

Options:

(A). Both A and R are true, and R is the correct explanation of A.
(B). Both A and R are true, but R is not the correct explanation of A.
(C). A is true, but R is false.
(D). A is false, but R is true.

Correct Answer: (A). Both A and R are true, and R is the correct explanation of A.

Question 6:

Assertion (A): In a right triangle, the square of the hypotenuse is equal to the sum of the squares of the other two sides.

Reason (R): This is the Pythagoras Theorem.

a2+b2=c2

Options:

(A). Both A and R are true, and R is the correct explanation of A.
(B). Both A and R are true, but R is not the correct explanation of A.
(C). A is true, but R is false.
(D). A is false, but R is true.

Correct Answer: (A). Both A and R are true, and R is the correct explanation of A.

Question 7:

Assertion (A): If the square of one side of a triangle equals the sum of the squares of the other two sides, then the triangle is right-angled.

Reason (R): This is the converse of the Pythagoras Theorem.

Options:

(A). Both A and R are true, and R is the correct explanation of A.
(B). Both A and R are true, but R is not the correct explanation of A.
(C). A is true, but R is false.
(D). A is false, but R is true.

Correct Answer: (A). Both A and R are true, and R is the correct explanation of A.

Question 8:

Assertion (A): Two triangles with equal corresponding sides are always similar.

Reason (R): Equal corresponding sides imply congruent triangles.

Options:

(A). Both A and R are true, and R is the correct explanation of A.
(B). Both A and R are true, but R is not the correct explanation of A.
(C). A is true, but R is false.
(D). A is false, but R is true.

Correct Answer: (B). Both A and R are true, but R is not the correct explanation of A.

Question 9:

Assertion (A): The altitude drawn to the hypotenuse of a right triangle divides it into two similar triangles.

Reason (R): Each smaller triangle has one angle equal to the corresponding angle of the original triangle.

Options:

(A). Both A and R are true, and R is the correct explanation of A.
(B). Both A and R are true, but R is not the correct explanation of A.
(C). A is true, but R is false.
(D). A is false, but R is true.

Correct Answer: (A). Both A and R are true, and R is the correct explanation of A.

Question 10:

Assertion (A): The ratio of perimeters of two similar triangles is equal to the ratio of their corresponding sides.

Reason (R): All corresponding sides of similar triangles are proportional.

Options:

(A). Both A and R are true, and R is the correct explanation of A.
(B). Both A and R are true, but R is not the correct explanation of A.
(C). A is true, but R is false.
(D). A is false, but R is true.

Correct Answer: (A). Both A and R are true, and R is the correct explanation of A.

Question 11:

Assertion (A): If two triangles are congruent, they are also similar.

Reason (R): Congruent triangles have equal corresponding sides and angles.

Options:

(A). Both A and R are true, and R is the correct explanation of A.
(B). Both A and R are true, but R is not the correct explanation of A.
(C). A is true, but R is false.
(D). A is false, but R is true.

Correct Answer: (A). Both A and R are true, and R is the correct explanation of A.

Question 12:

Assertion (A): A line drawn parallel to one side of a triangle forms a smaller triangle similar to the original triangle.

Reason (R): Corresponding angles formed are equal.

Options:

(A). Both A and R are true, and R is the correct explanation of A.
(B). Both A and R are true, but R is not the correct explanation of A.
(C). A is true, but R is false.
(D). A is false, but R is true.

Correct Answer: (A). Both A and R are true, and R is the correct explanation of A.

Question 13:

Assertion (A): The triangles with sides (3,4,5) form a right triangle.

Reason (R): The sides satisfy:32+42=52

Options:

(A). Both A and R are true, and R is the correct explanation of A.
(B). Both A and R are true, but R is not the correct explanation of A.
(C). A is true, but R is false.
(D). A is false, but R is true.

Correct Answer: (A). Both A and R are true, and R is the correct explanation of A.

Question 14:

Assertion (A): The ratio of the areas of two similar triangles with side ratio 2 : 3 is 4 : 9.

Reason (R): Area ratio equals the square of the side ratio.

Options:

(A). Both A and R are true, and R is the correct explanation of A.
(B). Both A and R are true, but R is not the correct explanation of A.
(C). A is true, but R is false.
(D). A is false, but R is true.

Correct Answer: (A). Both A and R are true, and R is the correct explanation of A.

Question 15:

Assertion (A): Two triangles are similar if their corresponding sides are proportional.

Reason (R): This is the SSS similarity criterion.

Options:

(A). Both A and R are true, and R is the correct explanation of A.
(B). Both A and R are true, but R is not the correct explanation of A.
(C). A is true, but R is false.
(D). A is false, but R is true.

Correct Answer: (A). Both A and R are true, and R is the correct explanation of A.

Download PDF - Assertion And Reason Questions For Class 10 Maths Chapter 6 Triangles

Frequently Asked Questions on Triangles Class 10 Chapter 5 Assertion And Reason Questions

1. What are similar triangles?

Two triangles are similar if their corresponding angles are equal and corresponding sides are proportional.

2. What are the criteria for similarity of triangles?

The three similarity criteria are:

  • AA (Angle-Angle)
  • SAS (Side-Angle-Side)
  • SSS (Side-Side-Side)

3. What is the Basic Proportionality Theorem (BPT)?

If a line is drawn parallel to one side of a triangle intersecting the other two sides, it divides those sides in the same ratio.

4. What are common mistakes in Triangle Assertion And Reason questions?

  • Confusing congruence with similarity
  • Incorrect proportional ratios
  • Errors in theorem application

5. Why are triangles important in Class 10 Maths?

Triangles form the foundation for trigonometry, geometry, construction, and coordinate geometry.

6. What is the difference between congruent and similar triangles?

  • Congruent triangles have the same shape and size.
  • Similar triangles have the same shape but may have different sizes.
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