# Coplanar

Points or lines are said to be
**
coplanar
**
if they lie in the same plane.

**
Example 1:
**

The points $P$ , $Q$ , and $R$ lie in the same plane $A$ .

They are
*
coplanar
*
.

**
Example 2:
**

The points $P$ , $Q$ and $R$ lie in the plane $A$ and the point $S$ lies on the plane $B$ .

They are
*
non coplanar
*
.

**
Example 3:
**

The two lines $\stackrel{\leftrightarrow}{PQ}$ and $\stackrel{\leftrightarrow}{RS}$ lie in the same plane $A$ .

They are
*
coplanar
*
.

**
Example 4:
**

The two lines $\stackrel{\leftrightarrow}{PQ}$ and $\stackrel{\leftrightarrow}{UV}$ are skew lines.

They are
*
non coplanar
*
.