Class 9 RS Aggarwal Chapter-8 Triangles Solutions - Free PDF Download
FAQs on RS Aggarwal Class 9 Solutions Chapter-8 Triangles
1. How do RS Aggarwal Solutions for Class 9 Maths Chapter 8 help with difficult triangle problems?
Vedantu's RS Aggarwal Solutions for Class 9 Maths Chapter 8 help by breaking down complex problems into simple, understandable steps. They provide detailed explanations for each theorem and proof, focusing on the correct methodology as per the CBSE 2025-26 guidelines. This approach helps you identify the appropriate congruence rule or property needed to solve even the most challenging questions.
2. What are the main congruence criteria for triangles covered in RS Aggarwal Class 9 Chapter 8?
The primary criteria for proving the congruence of triangles in this chapter are:
- SAS (Side-Angle-Side): Two sides and the included angle of one triangle are equal to the corresponding sides and included angle of the other.
- ASA (Angle-Side-Angle): Two angles and the included side of one triangle are equal to the corresponding angles and included side of the other.
- AAS (Angle-Angle-Side): Two angles and a non-included side of one triangle are equal to the corresponding angles and non-included side of the other.
- SSS (Side-Side-Side): All three sides of one triangle are equal to the corresponding three sides of the other.
- RHS (Right-angle-Hypotenuse-Side): In two right-angled triangles, the hypotenuse and one side of one triangle are equal to the hypotenuse and corresponding side of the other.
3. What is the difference between the ASA and AAS congruence rules, and how do you decide which one to use?
The key difference lies in the position of the side. In the ASA (Angle-Side-Angle) rule, the side must be the included side, meaning it is located between the two angles. In the AAS (Angle-Angle-Side) rule, the side is a non-included side. You can use AAS when you know two angles and a side that is not between them. Essentially, if you know any two angles of a triangle, you can find the third, which often allows you to convert an AAS situation into an ASA one.
4. When applying the SAS congruence rule, what is the most common mistake students make?
The most common mistake when using the SAS (Side-Angle-Side) rule is failing to ensure the angle is the included angle. For this rule to be valid, the angle you are using for comparison must be the one formed by the two sides you are comparing. For instance, to prove ∆ABC ≅ ∆PQR using SAS with sides AB=PQ and BC=QR, you must prove that ∠B = ∠Q, as it is the angle between the given sides.
5. Why is the RHS congruence criterion only applicable to right-angled triangles?
The RHS criterion is specific to right-angled triangles because its components are defined by them. 'R' stands for a Right angle (90°), and 'H' stands for the Hypotenuse, which is the side opposite the right angle. This unique combination of a 90° angle, the longest side (hypotenuse), and one other corresponding side provides enough information to guarantee congruence. This specific set of conditions does not ensure congruence in non-right-angled triangles.
6. How do you prove that the angles opposite to equal sides of a triangle are equal?
To prove this theorem for a triangle ABC where AB = AC, you can follow these steps:
- First, draw an angle bisector of ∠A that meets the side BC at a point D.
- Now, consider the two triangles formed: ΔABD and ΔACD.
- You have AB = AC (given).
- ∠BAD = ∠CAD (by construction, as AD is the angle bisector).
- AD = AD (common side).
- Therefore, by the SAS congruence rule, ΔABD ≅ ΔACD.
- Since the triangles are congruent, their corresponding parts are equal. Hence, ∠ABD = ∠ACD, which means ∠B = ∠C.
7. Where can I find reliable, step-by-step solutions for all exercises in RS Aggarwal Class 9 Chapter 8?
Vedantu provides comprehensive, step-by-step solutions for all exercises in RS Aggarwal Class 9 Chapter 8, Triangles. These solutions are prepared by subject matter experts to ensure accuracy and adherence to the CBSE 2025-26 syllabus. Each answer explains the logic and method, making it easier for students to prepare for exams and clarify their doubts effectively.











