Perpendicular lines are drawn by fitting the hypothenuse of the triangle to the T-square at an angle, or another triangle. Then, turn the triangle so that the hypothenuse is perpendicular to the line.

Drawing Perpendicular Lines Using T-square and Triangle

Perpendicular lines are drawn by fitting the hypothenuse of the triangle to the T-square at an angle,…

Illustration of two parallel planes. "Two planes perpendicular to the same straight line are parallel."

Parallel Planes

Illustration of two parallel planes. "Two planes perpendicular to the same straight line are parallel."

Two parallel planes perpendicular to a line (AB).  "A straight line perpendicular to one of two parallel planes is perpendicular to the other also."

Parallel Planes

Two parallel planes perpendicular to a line (AB). "A straight line perpendicular to one of two parallel…