Question

what is the measure of angle d? 52° 54° 57° 126°

Explanation:

Step1: Recall sum of angles in quadrilateral

The sum of the interior angles of a quadrilateral is $360^{\circ}$.

Step2: Set up angle - sum equation

Let $\angle A = 128^{\circ}$, $\angle B=126^{\circ}$, $\angle C = 54^{\circ}$, and $\angle D$ be the unknown angle. Then $\angle A+\angle B+\angle C+\angle D=360^{\circ}$.

Step3: Solve for $\angle D$

$\angle D=360^{\circ}-\angle A - \angle B-\angle C$. Substitute the values: $\angle D=360^{\circ}-128^{\circ}-126^{\circ}-54^{\circ}$. First, $128^{\circ}+126^{\circ}+54^{\circ}=308^{\circ}$. Then $\angle D = 360^{\circ}-308^{\circ}=52^{\circ}$.

Answer:

$52^{\circ}$