#### Parallel & Perpendicular Lines in coordinate Geometry

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Parallel & Perpendicular Lines in coordinate Geometry

PARALLEL & PERPENDICULAR LINES IN
COORDINATE GEOMETRY
What
types of slopes do parallel
lines have?
What
types of slopes do
perpendicular lines have?
Parallel
lines have the same
slope.
Perpendicular
lines have slopes
that are opposite reciprocal.
ANSWER THE FOLLOWING QUESTIONS
WITH YOUR GROUP MEMBERS
What is the slope of a line parallel to y = 3x – 7?
What is the slope of a line perpendicular to
y = -2x + 6?
What is the slope of a line parallel to y = 9?
What is the slope or a line perpendicular to
y = -x/5 + 11
Find
the equation of a line that
is parallel to the line y = -7x + 4
and passes through the point
(-4, 6)
STEP ONE
Identify
the slope and point
Slope is -7
Point is (-4, 6)
If we have a point and a slope, what form of an
equation do we need to use?
STEP TWO
Plug
into point – slope form
y – y1 = m(x – x1)
y
– 6 = -7(x – -4)
STEP THREE
Finish
by putting equation into
slope-intercept form
y
– 6 = -7(x – -4)
y – 6 = -7(x + 4)
y – 6 = -7x – 28
y = -7x – 22
Find
the equation of a line that
is perpendicular to the line
y = 3x – 9 and passes through
the point (-1, 8)
STEP ONE
Identify
the slope and point
1
Slope is 3
Point is (-1, 8)
If we have a point and a slope, what form of an
equation do we need to use?
STEP TWO
Plug
into point – slope form
y – y1 = m(x – x1)
y
– 8 = (x – -1)
1
y – 8 = x – 3
1
3
1
3
STEP THREE
Finish
by putting equation into
slope-intercept form
y
– 8 = (x – -1)
y – 8 = (x + 1)
1
y – 8 = x – 3
26
1
y = 3 x + 3
1
3
1
3
1
3
TRY ON YOUR OWN!!!
Find
the equation of a line that is
perpendicular to the line y = -2x – 9 and
passes through the point (-4, 6)
Find
the equation of a line that is parallel
to the line y = 3x + 5 and passes through
the point (-9, 1)
TIME TO PROCESS WHAT YOU
LEARNED
THINK TO YOURSELF!!!
Think of a three word statement that sums up something
you learned from this lecture.
DO NOT SAY IT OUT LOUD!!!
We will go around the room and share in two
minutes