adjacent=9.2mm hypotenuse=13.9mm what is angle ≺CAB?
cos of any angle in triangle = adjacent side / hypotenuse
In this case;
cos ≺CAB = 9.2 / 13.9 = 0.6618705036
≺CAB = cos ⁻ ¹ ( 0.6618705036 )
≺CAB = 48° 33' 26"
cos ⁻ ¹ is otherwise called arcus cosine so you can write:
≺CAB = arccos ( 0.6618705036 )
≺CAB = 48° 33' 26"