Picture a triangle with hypotenuse 12 ft and "opposite side" 3 ft. Then the sine of the unknown angle is sin x = (3 ft) / (12 ft), or sin x = 1/4.
Apply the inverse sine function to determine the angle x.
Using my calculator, I got x= 0.253 radian. You could change this into degrees, if you wish, by mult. this result by (180 degrees) / (pi radians).