Given:
To find:
The obtuse angle between the given pair of straight lines.
Solution:
The slope intercept form of a line is
...(i)
where, m is slope and b is y-intercept.
The given equations are
On comparing these equations with (i), we get
Angle between two lines whose slopes are is
Putting and
, we get
Now,
and
and
and
, so it is an obtuse angle and
, so it is an acute angle.
Therefore, the obtuse angle between the given pair of straight lines is 120°.