Explanation:
Hey there!
From the above right angled triangle ABC;
Taking Angle ABC as reference angle;
Angle ABC = ???
Perpendicular (p) = AC = 15
Base (b) = AB = 47
Now;
Taking ratio of sin;

Keep value;

Simplify it;

Take tan to next side;
Angle ABC (alpha) = tan'(0.3191489)
Therefore, the measure of angle ABC is 17.70°.
Hope it helps!