Q. 103.7( 3 Votes )

# Each pair of arms of two angles is parallel to each other. Let’s prove either these angles are equal in measurement or they are supplementary.

Answer :

Given that BC||DE.

∠ABC+∠CBD=180° (straight angle)

⇒ ∠ABC=180°-∠CBD ……………….(1)

Also, draw FG||BD,

∴ BFGD is a parallelogram

So, ∠CBD+∠BDE=180° (co-interior angles)

⇒ ∠BDE =180°-∠CBD ……………….(2)

From (1) and (2)

⇒ ∠ABC=∠BDE

Hence Proved.

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If AB||CD then let’s write the measurement of the angles given below:

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West Bengal - MathematicsExamining the measurement of the angles given below let’s conclude logically AB&CD are parallel.

West Bengal - Mathematics

Examining the measurement of the angles given below let’s conclude logically AB&CD are parallel.

West Bengal - Mathematics