Pix for Perpendicular

1. Right angles are all around us.

2. The sign of the cross is everywhere we look.

3. Two perpendicular lines divide the screen into four equal quadrants.

4. The perpendicular is not very common in nature, but it is abundant in human artifacts.

5. There are ninety degrees in a right angle.

6. xxyy - bbxx - aayy = 0

7. Mutually perpendicular pairs of vectors of equal magnitude from a fixed origin.