<u>Angle A = 30 degrees</u>
1) Use the Pythagorean Theorem: 
--> 
--> 144 + 48 = 
--> 192 = 
--> AC = 
2) Figuring out the type of triangle it is
There's a formula on the sides of a certain type of triangle:
--> Hypotenuse: a, Short Leg: a/2, Longer Leg: a/2 * 
That type of triangle perfectly matches the sides of our triangle: 12,
, 
Therefore, this triangle is a 30, 60, 90 triangle.
3) Finding the measure of angle A
--> Angle B is given: 90 degrees
--> The angle that's between Sides AB and AC is 30 degrees
Finally, we can conclude that Angle A is 30 degrees