Let `a=cos 10^@, b=cos 50^@ and c=cos 70^@`The value of `(b+c)` is equal to:

cos 10^(@) cos 30^(@) cos 50^(@) cos 70^(@) =

The value of cos ^(2) 10^(@) - cos 10^(@) cos 50^(@) + cos ^(2) 50^(@) is equal to

In a triangle ABC,if (2(sin B-sin C))/(cos B+cos C)=(sin A)/(1-cos A) then the value of (b)/(c) is equal to

The value of cos ^(2) 10^(@) cos 50^(@) + cos ^(2) 50^(@) is equal to

if sin A+sin B=C and cos A+cos B=D and C,D!=0 then the value of sin(A+B) is equal to

In triangle ABC, if (2(sin B-sin C))/((cos B+cos C))=(sin A)/(1-cos A) then the value of (b)/(c). is equal to

In a Delta ABC,a=5,b=3 and c=7, then the value of 3cos C+7cos B is equal to

cos 10^(@) cos 30^(@) cos 50^(@) cos 70^(@) =(3)/(16)

If A+B+C=pi and cos A=cos B cos C then tan B tan C is equal to