# SPACE SUMMARY

### PROPERTIES AND RULES

## Also,

*If two planes are parallel, then every line perpendicular to one is perpendicular to the other.**if two planes are perpendicular to the same line, then they are parallel.**If two lines are parallel, then every plane perpendicular to one is perpendicular to the other.**If two lines are perpendicular to the same plane, then they are parallel.*

## PERPENDICULAR PLANES

## 1.A line l is perpendicular to plane A if l is perpendicular to all of the lines in plane A that intersect l. A plane B is perpendicular to a plane A if plane B contains a line that is perpendicular to plane A. | ## 2.If two planes are perpendicular to the same plane, then the two planes either intersect or are parallel: plane B ⊥ plane A, plane C ⊥ plane A, and plane B and plane C intersect along line l. | ## 3.Two intersecting planes that are perpendicular to the same plane: plane B ⊥ plane A, plane C ⊥ plane A, and plane B // plane C. |

## 1.

A line l is perpendicular to plane A if l is perpendicular to all of the lines in plane A that intersect l. A plane B is perpendicular to a plane A if plane B contains a line that is perpendicular to plane A.

## 2.

If two planes are perpendicular to the same plane, then the two planes either intersect or are parallel: plane B ⊥ plane A, plane C ⊥ plane A, and plane B and plane C intersect along line l.