Question

What is the measure of a°?

Answer 1

Answer:

The correct answer is C. 129.

Step-by-step explanation:

Let's recall that the Inscribed Quadrilateral Theorem states that a quadrilateral is inscribed in a circle if and only if the opposite angles are supplementary.

In the case of the inscribed quadrilateral ABCD in the graph attached, we have that:

m∠C= 51°, therefore its supplementary angle, ∠A, should be the difference between 180° and m∠C.

m∠C= 180° - m∠A

Replacing with the real values:

51 = 180 - m∠A

m∠A = 129°

The correct answer is C. 129.