1.

In the given figure, if l//m , then what type of a triangle is ABC ? A. EquilateralB. IsoscelesC. ScaleneD. Right angled.

Answer» Correct Answer - B
Given `l||m` ,
`angleBCA=angleDEC=80^(@)` ( corresponding angles )
`angleCBA=angleEDB=50^(@)` ( corresponding angles )
`angleBCA+angleCBA+angleBAC=180^(@)`
`implies 80^(@)+50^(@)+angleBAC=180^(@)`
`implies angleBAC=50^(@)`
`:.` In `DeltaABC, angleA=angleB=50`
`implies DeltaABC` is isosceles.
Hence, the correct option is (b).


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