Question

Trapezium ABCD is such that AB is parallel to CD. Is this trapezium an isosceles trapezium?

Statement (I): ∠B and ∠D are supplementary
Statement (II): The quadrilateral is inscribed inside a circle

1. If the question can be answered with statement I alone but not statement II alone, or can be answered with statement II alone but not statement I alone
2. If the question cannot be answered with statement I alone or with statement II alone, but can be answered if both statements are used together
3. If the question can be answered with either statement alone
4. If the question cannot be answered with the information provided

Explanatory Answer

Statement (I): ∠B and ∠D are supplementary.
SUFFICIENT. If two base angles are equal, then the trapezium has to be isosceles.

Statement (II): The quadrilateral is inscribed inside a circle.
SUFFICIENT. All trapeziums inscribed in circles have to be isosceles. (Think about the proof for this)

Answer Choice (C)