Question

arms of ba and bc angle abc are respectively parallel to arms of ed andef of. angle def

Answer 1

Given AB || DE, BC || EF 

To prove: ∠ABC +∠DEF = 180o 

Construction: produce BC to intersect DE at M 

Proof: Since AB || EM and BL is the transversal 

∠ABC = ∠EML [Corresponding angle] ……(i) 

Also, EF || ML and EM is the transversal 

By the property of co-interior angles are supplementary 

∠DEF + ∠EML = 180o ...........(ii)

From (i) and (ii) we have 

∠DEF + ∠ABC =180o

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