If ```Delta` represents the area of acute angled triangle ABC, then `sqrt(a^2b^2-4Delta^2)+sqrt(b^2c^2-4Delta^2)+sqrt(c^2a^2-4Delta^2)=` (a) `a^2+b^2+c^2` (b) `(a^2+b^2+c^2)/2` (c) `a bcosC+b ccosA+c acosB` (d) `a bsinC+b csinA+c asinB`