If `a+b+c=13` , `a^2+b^2+c^2=69` , then find `a b+b c+c a` . `-50` (b) 50 (c) 69 (d) 75

If a+b+c=13,a^(2)+b^(2)+c^(2)=69, then find ab+bc+ca.-50 (b) 50 (c) 69 (d) 75

If a + b + c = 13, a^2 + b^2 + c^2 = 69, " then find " ab + bc + ca .

If a + b + c= 12 and a^(2) + b^(2) + c^(2) = 50 , find ab + bc + ca

If a^2+b^2+c^2=20\ \ a n d\ a+b+c=0, find a b+b c+c a

If a^2+b^2+c^2-a b-b c-c a=0, then (a) a+b=c (b) b+c=a (c) c+a=b (d) a=b=c

If   ( a -5 )^2 + ( b - c )^2 + ( c - d )^2 + ( b + c + d - 9 )^2 = 0 , then find the value of ( a + b + c ) ( b + c + d ) is

If a^(2) + b^(2) + c^(2) = 50 and ab +bc + ca= 47 , find a + b+ c

In A B C ,if a=10 and bcotB+ c cotC=2(r+R) then the maximum area of A B C will be (a) 50 (b) sqrt(50) (c) 25 (d) 5

In A B C ,if a=10 and bcotB+ c cotC=2(r+R) then the maximum area of A B C will be (a) 50 (b) sqrt(50) (c) 25 (d) 5

If a= 89, b= -69, c= 8 then the value of 9(a+b)^(2) +49 c^(2) -42 (a+b)c is