# Ex.7.2 Q9 Congruence of Triangles - NCERT Maths Class 7

## Question

If \(ΔABC\) and \(ΔPQR\) are to be congruent, name one additional pair of corresponding parts. What criterion did you use?

## Text Solution

**What is unknown?**

Name one additional pair of corresponding parts and the criterion used.

**Reasoning:**

In this question, if two triangles \(ΔABC\) and \(ΔPQR\) are to be congruent, we must name one additional pair of corresponding part and the criterion used. For better understanding of this question, visualize it with the help of figure. In triangles \(ΔABC\) and \(ΔPQR\) it is given that, \(\angle B = 90^\circ\) and \(\angle Q= 90^\circ\,, \angle C =\angle R.\) Now, find out the side between these two angles that would be your one additional pair of corresponding part. Also, by reminding the criterion based on angle and the side of a right- angled triangle, you can find out the criterion used.

**Steps:**

In triangle \(ΔABC\) and \(ΔPQR\) are congruent.

\(\angle B = 90^\circ\) and \(\angle Q= 90^\circ\,, \angle C =\angle R.\)

Then one additional pair is,

\(\overline {BC} = \overline{QR}\)

Therefore,

\(ΔABC ≅ PQR\) (By \(ASA\) congruence rule)