Three vectors $$\overrightarrow A $$ = a$$\widehat i$$ + $$\widehat j$$ + $$\widehat k$$; $$\overrightarrow B $$ = $$\widehat i$$ + b$$\widehat j$$ + $$\widehat k$$ and $$\overrightarrow C $$ = $$\widehat i$$ + $$\widehat j$$ + c$$\widehat k$$ are mutually perpendicular ($$\widehat i$$, $$\widehat j$$ and k are unit vectors along X, Y and Z-axes respectively). The respective values of a, b and c are

The vectors $$\overrightarrow A $$ and $$\overrightarrow B $$ are such that | $$\overrightarrow A $$ + $$\overrightarrow B $$ | = | $$\overrightarrow A $$ $$-$$ $$\overrightarrow B $$ |. The angle between the two vectors will be