Question

prove that sum of interior angles of a triangle is equal to 180 degree​

Answer 1

Given :-

• A regular triangle ABC .

To Find :-

• The sum of interior angles of a triangle is equal to 180 degree.

Construction :-

Through point A draw EF || BC.

Proof :-

In a given triangle ABC,

∠ABC = ∠EAB {alternate angles }

∠BCA = ∠FAC {alternate angles }

∠EAB + ∠BAC + ∠FAC = 180° {sum of linear angles}

∠FAC = ∠EAB

∠FAC = ∠BCA

So, ∠ABC + ∠CAB + ∠BCA = 180° .

Hence , Proved the angle sum property of a triangle.

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