Determine the positive angle that the straight line makes with the positive direction of the -axis, given that passes through the two points
We know that the slope of a straight line is the tangent of the positive angle that the line makes with the positive .
We know also that the slope of a line passing through 2 points and is given by
Using the coordinates of and in the above formula we get
Let the required angle be .
Using the calculator, we get .