If `a+b+c=4` and `a^(2)+b^(2)+c^(2)+3(ab+bc+ac)=21` where `a, b, c in R` then `ab+bc+ca=`

(a+b+c)(a^(2)+b^(2)+c^(2)-ab-bc-ac)

If a+b+c=9anda^(2)+b^(2)+c^(2)=21 , then ab+bc+ca is equal to

If a^(2) +b^(2) +c^(2) = ab + bc + ca then (a+b)/(c ) + (b+c)/(a) + (c+a)/(b) =?

If a^(2) +b^(2) +c^(2) = ab + bc + ca then (c )/(a+b) + (b)/(a +c)+ (c )/(a+b) = ?

If a^(2)+b^(2)+c^(2)=ab+bc+ca where a,b,c are the sides of a triangle,then the largest angle of that triangle is

If a^(2)+b^(2)+c^(2)-ab-bc-ca=0, then a+b=c( b) b+c=ac+a=b(d)a=b=c

If a+b+c=0 and a^(2)+b^(2)+c^(2)=1, then (a) ab+bc+ca=(1)/(2)( b) ab+bc+ca=(1)/(2)( c) a^(4)+b^(2)+c^(4)=(1)/(2)( d) a^(4)+b^(4)+c^(4)=(3)/(2)