Ch 7 covers triangle congruence — when two triangles are exactly equal. Students learn the five congruence criteria (SAS, ASA, AAS, SSS, RHS), properties of isosceles triangles, and triangle inequality relations.
Two triangles are congruent if they are equal in shape and size. Five criteria: SAS (two sides and included angle), ASA (two angles and included side), AAS (two angles and non-included side), SSS (all three sides), RHS (right angle, hypotenuse, one side).
If two sides of a triangle are equal, the angles opposite to them are equal (and conversely). In an equilateral triangle, all angles are 60°.
In any triangle: the side opposite the larger angle is longer. Conversely, the angle opposite the longer side is larger. The sum of any two sides is greater than the third side.
Download: https://ncert.nic.in/textbook/pdf/iemh107.pdf | Complete book: https://ncert.nic.in/textbook/pdf/iemh1ps.zip
CPCT stands for "Corresponding Parts of Congruent Triangles." Once two triangles are proved congruent, all their corresponding sides and angles are equal — this is CPCT.
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