Find the angle of intersection when the line through the points $(3,4)$ and $(-5,0)$ intersects the line through $(0,0)$ and $(-5,0)$.
So we have points (3,4) and (-5,0) . Its equation of line would be
2y = x + 5
The other is (0,0) and (-5,0) . Its equation would be
y = 0
Thus it is the x axis.
So basically since we observe that (-5,0) is the intersection point the question is to calculate the slope of second line..
Thus we get tan( theta ) = 1/2
and get theta = tan inverse(1/2) to get the acute angle of intersection....