Answer:
53°
Explanation:
ΔABC is a right triangle (one of the angles is 90°).
You can use SOH-CAH-TOA to find an angle:
Sine = Opposite / Hypotenuse
Cosine = Adjacent / Hypotenuse
Tangent = Opposite / Adjacent
In this case, we want to find ∠A. We know the lengths of the opposite side and the hypotenuse. Therefore, we should use sine.
sin A = 12 / 15
m∠A = sin⁻¹(12/15)
m∠A ≈ 53°
Alternatively, you could use Pythagorean theorem to find the third side, then use either cosine or tangent to find m∠A.