# Relative Position of Graphs of the Linear Functions

Suppose we are given two linear functions y=k_1x+b_1 and y=k_2x+b_2.

Graphs of these functions are lines.

These lines intersect if k_1!=k_2. In particular, if k_1k_2=-1 then lines are perpendicular.

These lines are parallel if k_1=k_2. In particular, if b_1=b_2 then lines are same.

For example, lines y=2x+3 and y=2x-4 are parallel. Lines y=4x+3 and y=-0.25x+7 are perpendicular.