Question

prove that the sum of three angle of a triangles a triangle is 180
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Answer 1

To prove :-

• Sum of all angles of a triangle is 180°

Construction :-

Through A,draw a line DAE || BC

Proof :-

→ DAE || BC and AB is the transversal.

→ ∠4 = ∠2 [ alternate interior angle ]

DAE || BC and AC is transversal.

→ ∠5 = ∠3 [ alternate interior angle ]

Now,DAE is a straight line.

→ ∠4 + ∠1 + ∠5 = 180° [ angles on the same side of DAE at point A ]

→ ∠1 + ∠4 + ∠5 = 180°

→ ∠1 + ∠2 + ∠3 = 180° [ °.°∠4 = ∠2 and ∠5 = ∠3]

Hence,sum of the angles of a triangle is 180°.

Note :- See the attachment for diagram.

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Remarks :-

• A triangle cannot have more than one right angle.

• A triangle cannot have more than one obtuse angle.

• In a right angle triangle,the sum of two acute angles is 90°.

Answer 2

Answer:

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Step-by-step explanation: