Question

theorem of chapter 7 class 9

Answer 1

theorem 1 Sides opposite to equal angles are equal.
theorem 2 Angels opposite to equal sides are equal.
if two triangle have these in common they will be congruent.
congruence rules..
ASA means angle side angle
SSS means sides
SAS means side angle side
RHS( in two right angles) means Rhight angle hypotenuse and side.
AAS means angle angle side

note that these congruent rule will work if two triangle have these in sequence in which they for eg if triangle have one angle one side and then one angle it will be ASA rule if it has two angle first than one side it will be AAS rule.

Then some inequality theorems

The sum of any two sides is greater than the third side.

If two sides of a triangle are unequal the opposite angle of longer side is largest.

in any triangle,the side opposite to the larger angle is longer

hope it helps^_^