Measure of the Angle between Two Straight Lines

The angle between the lines is 55.41°.

The angle between the two lines is given by

θ=β-α

.

Let

y=

m

1

x+

b

1

and

y=

m

2

x+

b

2

be the equations of two lines in the plane, with

m

1

and

m

2

the slopes of the lines. The angle

θ

between them is given by

θ=

-1

tan

m

1

-

m

2

1+

m

1

m

2

.