Calling 90 degrees a “right” angle is a little misleading. Yes, spatial coordinates should usually be based on perpendicular lines. But 90 degrees is often just one angle among many, and perpendicular may not be right for the job.
– Gray button (upper left corner) reveals widgets, –
– above post (on phone) or beside it (on desktop). –
– above post (on phone) or beside it (on desktop). –
Perpendicular ~ Pic and a Word Challenge #269
The ceiling should be perpendicular to the wall
(and the wall to the floor).
Even the klutz who built my house got it right.
The right angle for slicing a pizza depends on
how many slices are needed.
© sabelnik | 123RF Stock Photo
Willing to count a circle as a “line” perpendicular to any chosen straight line thru the center? (I am.) If so, then spatial coordinates should almost always (not just usually) be based on perpendicular lines. Want to navigate on a really big pizza? Use polar coordinates.
Mellow Curmudgeon 
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