Question

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

Explanation:

Step1: Recall properties of a square

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

Step2: Calculate $\angle BAC$

Since AC bisects $\angle BAD$, $\angle BAC=\frac{1}{2}\angle BAD$. Given $\angle BAD = 90^{\circ}$, then $\angle BAC=\frac{1}{2}\times90^{\circ}=45^{\circ}$.

Answer:

B. $45^{\circ}$