1. sin ∠YWX refers to the sin of the angle formed by the points YWX with X as the vertex
sin = opp/hyp
therefore sin ∠YWX = 40/41
2. cos ∠STR refers to the cosine of the angle formed by the points STR with T as the vertex
cos = adj/hyp
therefore cos ∠STR = 12/13
3. tan ∠YXZ refers to the tangent of the angle formed by the points YXZ with X as the vertex
tan = opp/adj
therefore tan ∠YXZ = d/c
4. tan ∠ZYX refers to the tangent of the angle formed by the points ZYX with Y as the vertex
tan = opp/adj
therefore tan ∠ZYX = c/d
