NCERT Exemplar Solutions
Class 10 - Mathematics - CHAPTER 6: Triangles - Exercise 6.2
Question 12

Question. 12

Is the following statement always true? “If an angle of one triangle equals an angle of another and two sides of one triangle are proportional to the corresponding two sides of the other triangle, then the triangles are similar.” Give reasons.

Answer:

Not always.

Detailed Answer with Explanation:

Let us go step by step:

Step 1: Recall the condition for SAS similarity of two triangles.

  • The angle between two sides of one triangle is equal to the angle between two sides of the other triangle.
  • The two sides of one triangle are proportional to the corresponding two sides of the other triangle.

If these two conditions are satisfied, then the triangles are similar.

Step 2: In the question, we are told:

  • One angle of the first triangle is equal to one angle of the second triangle.
  • Two sides of the first triangle are proportional to the corresponding two sides of the second triangle.

Step 3: This information is not enough unless the equal angle lies between the two proportional sides.

If the equal angle is the included angle between the two proportional sides, then the triangles will definitely be similar (by SAS similarity).

Step 4: But if the equal angle is not the included angle, then the triangles may or may not be similar. In fact, we can even draw counterexamples where similarity fails.

Final Conclusion: Therefore, the statement given in the question is not always true. It is true only when the equal angle is the included angle between the proportional sides.

NCERT Exemplar Solutions Class 10 – Mathematics – CHAPTER 6: Triangles – Exercise 6.2 | Detailed Answers