Question

Find the angle between x-axis and the line joining the points 3, - 1 and 4, - 2

Answer 1

45 degree. find slope of line and equate it to tan

Answer 2

Let A(3,-1) and B(4,-2) be the given points  

and we will consider m be the slope of the line AB.

m = -2-(-1)/4-3

= -2 + 1/1

= -1

[∴ m = (y₂ - y₁) / (x₂ - x₁)]

Now we will consider θ = m = -1

= - tan 45°

= tan (180° - 45°)

= tan 135°

θ = 135°

So the required angle is 135°