In Erercises 70-78, use either of the two methods developed in this section to find a fonnula for rn. Then use your result to find r 6. r. = 2r.,_1 + r- 2- 2r.,_3; ro = 3, r, I, and rz = 3

Chapter 9 Section 3 SNOW DAY PRESENTATION 02/24/2016 Chapter 9 Section 3 Terminology: Space- is an undefined term (like point, line and plane) Dihedral angle- angle formed when 2 planes meet Parallel- if the line doesn’t intersect the plane Perpendicular- if the line if intersects and is perpendicular to EVERY point in plane Two planes are parallel if they do not intersect Two planes are perpendicular if dihedral angle measures 90 degrees Polyhedral- figures in space whose sides are polygonal regions Faces- polygonal regions or sides Edges- 2 faces intersect