Pythagorean triplet and vectors

[you_of_eh]

Suppose that vectors A, B and C are related by A-B=C.

a) Is it possible that A-B=C? If so, draw the sort of situation when this is so. (A is the magnitude of A, B of B and C of C.)

b) Is it possible that C=A+B? If so, then draw the sort of situation when this is so.

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a) I used the Pythagorean triplet 3,4,5 for this situation.
b) I'm not sure but I think the question basically asks whether C can equal A+B and at the same time can C equal the square root of the sum of the squares of A and B. I'm having trouble getting my head around this.

 

[you_of_eh]

OK never mind, false alarm. For some reason I was thinking strictly in the form of triangles for my vector subtraction. I believe situation b) is possible if you have any two vectors of opposite direction.