In this unit, you will look at the face, edge, and vertex of a solid figure. You will learn the difference between "plane" figures and "solid" figures, and line symmetry.
Common Three-Dimensional Shapes
Properties of a 3-D Shape
Plane Figures
Plane figures are flat, solids are not.
These are plane figures.
Line Symmetry A lineof symmetry is a line that divides a figure into two congruent parts, each of which is the mirror images of the other. When the figure having a lineofsymmetry is folded along the lineof symmetry, the two parts should coincide.
You can draw a line straight down the middle of the butterfly and it will look exactly the same of both sides. The butterfly has a lineofsymmetry.
The first triangle has no lines of symmetry, the second has 1 line of symmetry, and the third has 3 lines of symmetry.
You can draw a line straight down the middle of the face and it will look exactly the same of both sides. The face has line symmetry.
