Find the angle between the x-axis and the line joining the points (3,−1) and (4,−2).
The slope of the line joining the points (3,−1) and (4,−2) is m=−2−(−1)4−3=−2+1=−1
Now the inclination (θ) of the line joining the points (3,1) and (4,2) is given by tanθ=−1
⇒θ=(90∘+45∘)=135∘
A slope of the line is an inclination with the x-axis.
Thus, the angle between x-axis and the line joining the points (3,1) and (4,2) is 135∘.