8.18 Parallel and perpendicular lines in linear functions
Parallel and perpendicular lines in linear functions
Parallel lines are lines with identical slope. In other words, these lines will never cross each other. Perpendicular lines will always pass through each other and form right angles at the interception. In this lesson, we will learn how to use information such as, points in lines and their slopes, to determine whether the lines are parallel, perpendicular or neither.
Lessons
Notes:
Parallel lines$$identical slope so they never intersect each other, unless overlapped.
Perpendicular lines$$two lines form right angles to each other when they intersect. If the slope of first line is ${a \over b}$, the slope of perpendicular line is the slope of perpendicular line is $ {b \over a}$. The product of the two slopes is 1.

a)
$m_1 = {2 \over 5}, m_2= {2 \over 5}$

b)
$m_1 = {1 \over5} , m_2 =  {5 \over 1}$

c)
$m_1 = {4 \over 7}, m_2 = {12 \over 21}$

d)
$m_1 =$undefined, $m_2 = 0$

e)
$m_1 =mn^{1}; m_2 =m^{1}b$


3.
Given the points of two lines, determine when the lines are parallel, perpendicular or neither.