CBSE Class 9 Maths Triangles
Congruence Criteria: SAS and ASA
SAS congruence Axiom: Two triangles are congruent to each other, if any two sides and the included angle of one triangle are equal to the corresponding sides and included angle of the other triangle.
ASA Congruence Rule: Two triangles are congruent, if two angles and the included side of one triangle are equal to the corresponding two angles and the included side of the other triangle. The congruence of triangles also holds even if the side is not included between the angles i.e. AAS holds.
Properties of Isosceles Triangle
Sides opposite to equal angles of a triangle are equal in length.
Angles opposite to equal sides of a triangle are equal in measure.
Congruence Criteria: SSS and RHS
If in two right triangles the hypotenuse and one side of one right triangle is equal to the hypotenuse and the corresponding side of the other right triangle, then the triangles are congruent by RHS Congruence Rule.
Inequalities in a Triangle
If two angles of a triangle are unequal, the greater side is opposite to the greater angle
The sum of any two sides of a triangle is greater than the third side.
The difference between any two sides of a triangle is less than the third side.
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