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karma
· New York, USA
Activity574 Answers135 Edits
@zor
Zor Shekhtman
commented
A square can be considered as a particular case of a rhombus, in which case we can say that rhombus can have all 4 angles to be #90^o#. Any other type of rhombus has no right angles.
on
How many right angles does a rhombus have?
@zor
Zor Shekhtman
commented
Yes, unfortunately, non-negativity of the #r# is not shared by many authors. In defense of this requirement I'd say that if negative #r# is allowed, any point on a plane, except the origin, would have two different pairs of polar coordinates: #(r, theta)# and #(-r, theta+pi)#. This is not a good property of any coordinate system to have two different numeric representation of the same point.
on
How do you graph #r=-1#?