Have a look at this: Trigonometry - Wikipedia, the free encyclopedia
Okay, well I have 2 fingers on an iPhone. The finger higher up will be called, "finger 2", where-as the finger lower down will be known as, "finger 1". Now suppose I were to take the x value of finger 2 along with the y value of finger 1 and create a third point called, "point 3" I would now have 3 points and an imaginary if you well, right triangle.
I want to find the angle of the intersection of line segment (point 3, finger 1) and line segment (finger 1, finger 2)... I want to find the angle of the intersection at the point, finger 1.
Also it needs to be in radians. What do I do to solve this, it has been ages since I've done trigonometry.
Diagram attached: .
In your equations to make things simpler we will define the following variables:
X1 = The x-value of finger 1.
Y1 = The y-value of finger 1.
X2 = The x-value of finger 2.
Y2 = The y-value of finger 2.
X3 = The x-value of point 3.
Y3 = The y-value of point 3.
Angle1 = The angle we are solving for.
Thank-you very much!