Question

prove that sum of 3 angle of ∆ is 180°​

Answer 1

Answer:

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Step-by-step explanation:

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Answer 2

Step-by-step explanation:

angle A + angle B + angle C = 180 degrees

angle 1 + angle 2 + angle 3 = 180 degrees

construction:

through A, draw a line " l "parallel to BC

proof:

since " l " parallel to BC therefore

angle 2 = angle 4.......... equation (1)

angle 3 = angle 5........... equation (2)

therefore

angle 2+ angle 3 = angle 4 + angle 5

angle 1 + angle 2+ angle 3 = angle 1+ angle 4 + angle 5[ adding both sides angle 1 ]

angle 1+ angle 2+ angle 3 = 180 degrees

hence the sum of 3 angles of triangle is 180 degrees