Bunuel wrote:

If AB||CD, what is the sum of angle ABC and angle BCD?

(1) ABC is more than 80°.

(2) BCD is 90°.

Given, AB || CD,

To find sum of angle ABC and angle BCD, we require the measure of any of the two angles.

Note:-(If the two lines crossed are parallel, the alternate angles are equal. Angle ABC=Angle BCD)

St1:- ABC is more than 80°.

No fixed measure of angle ABC.

Insufficient.

St2:-BCD is 90°

So, \(\angle{BCD}=\angle{ABC}=90°\)Therefore, sum of angle ABC and angle BCD can be determined.

Sufficient.

Ans. (B)

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Regards,

PKN

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