{a+b=11:12:13," then "cos A*cos B:cos C

With usual notation , if in triangle ABC, (b + c)/11 = (c + a)/12 = (a + b)/13 , then cos A : cos B : cos C =

With usual notations, if in a triangle ABC (b+c)/(11) = (c+a)/(12) = (a+b)/(13) , then cos A : cos B : cos C is :

With usual notations, if in a triangle ABC (b+c)/(11) = (c+a)/(12) = (a+b)/(13) , then cos A : cos B : cos C is :

If A+B+C=180^(@) then cos2A+cos2B+cos2C=1-4cos A cos B cos C 2.If A+B+C=0 then cos A+cos B+cos C=-1+4(cos A)/(2)(cos B)/(2)(cos C)/(2)

In a triangle ABC, if (b+c)/(11)=(c+a)/(12)=(a+b)/(13) then (cos A)/(l)=(cos B)/(m)=(cos C)/(n) where l,m,n are least positive integer.Find the value of (l+m+n).

Let A,B and C be three angles such that cos A+cos B+cos C=0 and if cos A cos B cos C=lambda(cos3A+cos3B+cos3C) then find the value of lambda