Question

In the figure given below, l || BC. Prove that a +b+c=180°.​

Answer 1

Answer:

Consider BC to be m, a b c angles be 1 ,2,3 respectively so,

Step-by-step explanation:

Given: l || m

RTP : angle 1 + angle 2 - angle 3 = 180 degree

Construction: Extend BC and let it intersect line 'm' at point 'F'. Let the angle BFD be 4.

proof: now,

angle 1 +angle 4 = 180 degree (co-int pair)

or angle 4= 180 - angle 1 -----(1)

IN triangle BCF ,

angle 3 + angle 4 = angle 2 (Exterior angle )

Applying equation 1, we have

angle 3 + 180- angle 1 =angle 2

or angle 1 + angle 2 -angle 3 = 180 (proved)

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Answer 2

Answer:

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Step-by-step explanation:

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