In a triangle ABC, if cosA+2 cosB+cosC=2 and the lengths of the sides opposite to the angles A and C are 3 and 7 respectively, then cos A-cos C is equal to

Question

In a triangle $A B C$ , if $\cos A + 2 \cos B + \cos C = 2$ and the lengths of the sides opposite to the angles $A$ and $C$ are $3$ and $7$ respectively, then $\cos A - \cos C$ is equal to

\frac{9}{7}

\frac{10}{7}

\frac{5}{7}

\frac{3}{7}

Solution

Please login to view the detailed solution steps...

Go to DASH