Question

Quadrilateral A B C D is shown. Sides A D and B C are parallel. Sides A B and C D are congruent. Angle A is 115 degrees.

What is the measure of ADC in quadrilateral ABCD?

45°
65°
115°
135°

Answer 1

• 65° if parallelogram

• 115° if trapezoid

Solution to the problem

Since no diagram attached there are two possible options.

Option 1

The quadrilateral is parallelogram.

In this case ∠A and ∠D sum up to 180°, therefore:

• ∠ADC = 180° - 115° = 65°

Option 2

The quadrilateral is isosceles trapezoid.

In this case ∠A is congruent with ∠D, therefore:

• ∠ADC = ∠A = 115°

Answer 2

115

Explanation: