Question

Norm of the sum of two vectors.

Answer 1

I tried to do but all I've got is:
\[\left| \left| v \right| \right|^2-2i I m (<v , w>) +\left| \left| w \right| \right|^2\]

Answer 2

I got:
\[2R e \left \langle v, -iw \right \rangle =i2R e \left \langle v, w \right \rangle \]
And if I understood correctly, Im(Something) isn't it real part multiplied by i, this is their imaginary part.