IXL - Slopes of parallel and perpendicular lines (Algebra 1 practice)

or

Line
m
has
a
slope
of
^–5
4
. Line
n
is
parallel
to
line
m . What
is
the
slope
of
line
n ?

Simplify your answer and write it as a proper fraction, improper fraction, or integer.

ref_doc_title.

or

Learn with an example

question

Line
r
has
a
slope
of
^–5
3
.
Line
s
has
a
slope
of
3
5
. Are
line
r
and
line
s
parallel
or
perpendicular?

parallel

perpendicular

neither

key idea

Parallel lines have the same slope.

Perpendicular
lines
have
slopes
that
are
opposite
reciprocals,
like
a
b
and
^–b
a
.
The
slopes
also
have
a
product
of
^- 1.

solution

The
lines
are
not
parallel
because
^–5
3
and
3
5
are
not
equal.

The lines are perpendicular because

^–5

3

and

3

5

are opposite reciprocals:

^–5

3

Take the slope of line r

^–3

5

Find the reciprocal

3

5

Find the opposite

Yes,

^–5

3

and

3

5

are opposite reciprocals.

So, the lines are perpendicular.

Looking for more? Try these:

Lesson: Equations of parallel and perpendicular lines

or

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Work it out

Not feeling ready yet? These can help:

AA.3Slope-intercept form: find the slope and y-intercept

K.2Find the slope from two points

Y.3Parallel, perpendicular, and intersecting lines

Lesson: Equations of parallel and perpendicular lines