Question

ADBA. 9°B. 10°C. 81°D. 91°99⁰CABCD is a quadrilateral. If mZC = (x²)°, find mZC..

Answer 1

Since ABCD is a quadrilateral, the sum of internal angles is equal to 360°.

Using this property, let's find the measure of angle C:

$\begin{gathered} A+B+C+D=360°\\ \\ 90+99+C+90=360\\ \\ C+279=360\\ \\ C=360-279\\ \\ C=81° \end{gathered}$

The measure of angle C is 81°, therefore the correct option is C.