If `a=b cos((2pi)/3)= c cos((4pi)/3),` then write the value o `a b+b c+c a`

If a=b cos((2pi)/3)= c cos((4pi)/3), then write the value of a b+b c+c a

If a=b(cos(2 pi))/(3)=(cos(4 pi))/(3), then write the value o ab+bc+ca

If a= b cos ""(2pi)/(3) = c cos ""(4pi)/(3), then the value of (ab+ bc +ca) is-

If a = b cos "" ( 2 pi)/ (3) = c cos "" (4 pi)/( 3) , then write the value of ab + bc + ca

If a cos theta = b cos ( theta+(2 pi)/3)= c cos ( theta+ (4pi)/3),"prove that" ab+bc+ca=0.

Circumcentre of DeltaABC (h,k) ,where co-ordinates of A=(2+cos(pi/3),3+sin(pi/3)) , B=(2+cos pi,3+sin pi) and C=(2+cos(4 pi/3),3+sin(4 pi/3)) , then the value of h^(2)+k^(2)=

If A, B, C, in (-(pi)/(2), (pi)/(2)) . Then prove that cos A+ cos B + cos C le 3/2 .

In triangle ABC, /_C = (2pi)/3 then the value of cos^2 A + cos^2 B - cos A.cos B is equal

If A + B+ C = 3 pi//2 , then the value of cos 2 A + cos 2 B + cos2 C is equal to