Hi, I am not sure if I should be posting here or on number theory, but there goes:

I am supposed to show geometrically (using an Argand diagram) that, for two complex numbers z and w, |z + w| is equal or larger than |z| - |w|.

It should follow the application of the triangle inequality (which is easy to show and I have no problem with).

My problem is how do I represent the subtration of modulus of z minus modulus of w? Treating them as vectors I can find the modulus of their addition or subtraction, but not the subtraction of the moduli???

Any suggestions would be greatly appreciated.

Thanks,

Maria