2. Two Lines Are Coplanar: Sometimes
The guitar neck represents a This highway intersection
plane. The strings represent represent two planes. One line
lines on that plane. This is is on each plane showing that
an example of when this two lines are not always
statement is true. coplanar.
3. A Line Intersects a Plane in One Point:
Sometimes
The pencil (line) is going The road shows a line that
through the paper (plane). intersects a plane at infinite
They intersect in a single points, or in a line.
point.
4. Two Planes Intersect in a Line:
Sometimes
The sides of the fence
These two shelves represent
each represent one plane
two parallel planes. Because
and they intersect in a
they are parallel they will
line at the corner of
never intersect.
the fence.
5. Two Planes Intersect in a Single Point:
Never
Because two planes go on forever, they are
infinite which means that if they
intersect, they will always intersect in
infinite points, or a line.Three planes can
intersect in a point, because there is only
one point that they all would intersect,
but every plane would intersect with one of
the others in a line.
6. Planes Have an Edge: Never
Planes don’t have edges because
they go on infinitely. Planes are
only drawn with edges so that
they are easier to visualize.
7. Two Points Are Collinear: Always
The two birds each represent a
point on the line (wire). You
can always draw a line between
any two points no matter where
they are placed on a plane.
8. Three Point Are Collinear: Sometimes
You can’t draw a line
Orion’s Belt shows through all three
three points, the stones, or points, on
stars, all in a this plane, or beach.
line. Therefore they are not
collinear.
9. Three Points Are Coplanar: Always
The three raindrops, points, are all
on the window or plane. No matter
where any three points are placed you
can always angle a plane to make all
three coplanar.
10. Four Points are Coplanar: Sometimes
Sometimes all four of
This horse is rearing and
the horses hooves, or
two of his hooves are not
points, are on the
on the ground. Therefore
ground, or plane.
all four of his hooves are
Therefore they are
not coplanar.
coplanar.
11. A Point is a Small, Filled Circle
THIS IS NOT A POINT!
A point has zero dimensions, and is
actually invisible. A very small filled
circle is used to represent a point
because people can’t draw something with
zero dimensions. A small filled circle
has two dimensions, therefore can not be
a real point.
