Express by an algebraic equation the statement that the line joining P(x,y)to the point (12,-5) has an inclination of arctan 1/3.
Analytic Geometry - Reiny, Saturday, December 11, 2010 at 10:23am
Did you know that the slope of a line is the tangent of the angle that the line makes with the x-axis?
So they are telling us that the slope of the line is 1/3
so (y+5)/(x-12) = 1/3
cross-multiply and simplify if you want the actual equation of the line.