abcd is a square. what is the measure of angle bac? 30° 45° 60° 90°

Answer:

B. $45^{\circ}$

Explanation:

Step1: Recall square properties

In square ABCD, $\angle ABC = 90^{\circ}$, and the diagonal AC bisects $\angle BAD$ and $\angle BCD$.

Step2: Calculate $\angle BAC$

Since AC bisects $\angle BAD$ and $\angle BAD=90^{\circ}$, then $\angle BAC=\frac{1}{2}\angle BAD$. So $\angle BAC = 45^{\circ}$.