Trigonometry (from Greek Τριγωνομετρία "tri = three" + "gon = angle" + "metr[y] = to measure") is a branch of mathematics that deals with triangles, particularly those plane triangles in which one angle has 90 degrees (right angle triangles). Trigonometry deals with relationships between the sides and the angles of triangles and with the trigonometric functions, which describe those relationships. Trigonometry has applications in both pure mathematics and in applied mathematics, and it is essential in many branches of science and technology.
No real mystery here, just calculate where the two lines intersect, and you have the coordinates.
(graph is a diagram only, and not drawn accurately - angles shown are between the line and the x-axis, and x-axis intercepts of each line are shown)
