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Mathematics
problems often deal with parallel and perpendicular lines.
Since these are such popular lines, it is important that we remember
some information about their slopes.
Parallel
Lines: (same
slope!)
Parallel
lines are marked with "feathers" to show that they are parallel.
These "feathers" look like "greater than" symbols.
Parallel
lines have the same slope.
y = 3x
+ 5
y = 3x - 7
y = 3x + 0.5
y = 3x |
These
lines are ALL parallel.
They all have the same slope (m).
(Remember y = mx + b.) |
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Example:
The slope of
is
 and
 .
Find the slope of
 .
Since the lines are parallel, the slopes are the same.
The slope of
is
. ANSWER |
Perpendicular
Lines:
(negative reciprocal slopes!)
Perpendicular
lines have negative reciprocal slopes.
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To get a
negative reciprocal of a number, flip the number over (invert) and
negate that value.
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These
lines are perpendicular.
Their slopes (m) are negative
reciprocals.
(Remember y = mx + b.) |
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Example:
The slope of
is
and
 .
Find the slope of
.
Since the lines are perpendicular, the slopes are negative
reciprocals.
The slope of
is
 .
ANSWER |
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