A, B and C are the points on a coordinate plane. The ΔABC is a right-angled triangle (right-angled at C ). If AC is parallel to the X-axis and the angle between AB and AC is 45o. The slope of AB is
1
If θ is the angle made by a line with the positive X-direction then the slope of the line is given by Tanθ.
Here, AC is parallel to X-axis. If a line makes an angle θ with AC then, the angle made by the line with X-axis is θ.
So, the slope of AB=Tan(45o)=1.