Page 74 - Math SL HB Sem 2

INES

LINE CLASSIFICATION

In 2-D, lines are either:

intersecting (r:reet at a point, with a unique
solution)

parallel (do not meet at all, i.e., no solution)

coincident 1i.e., the same iine, aii points satisfo

both equations) *-

In 3-D, lineS are either
. intersecting, paratlel or coincident (ioplanar, i.e., in the same plane)

. skew lines (not coplanar and can only occur in 3-D.)

1.e., or
0

point of intersection skew

Skew lines are any lines which are neither parallel nor intersecting.

o If the lines are parallel, the angle berween them is 0o.
o If the lines are intersecting, the angle between them is d.,, as shown.
. If the lines are skerv, there is still an angle that one line makes w'ith the other and it'
we translate one line to intersecl the other, the angle between the original lines is
defined as the angle between the intersecting lines,
i.e.,

line t
.--=_
linc I trirnslated
-....-...-.-....*
.-.=-.-} e
Iine 2
--.----.*-.-