Use vectors to prove that in `triangleABC` : `a=bcos C+c cos B`.

Use vectors to prove that in triangleABC : c=acos B+bcos A .

Use vectors to prove that in triangleABC : b=c cos A+a cos C .

Prove that in any triangle ABC,c=a cos B+b cosA

In any triangle ABC, then by vectors, prove that : a=b cos C+c cos B .

Using vector, prove that sin(A+B)=sinAcosB+cosAsinB

Prove that in any triangle ABC , c = a cos(360-B) + b cos(360-A)

In a triangleABC , if |(1,1,1),(1+sinA,1+sinB,1+sinC),(sinA+sin^2A,sinB+sin^2B,sinC+sin^2C)|=0 , then prove that triangleABC is an isosceles triangle.

In any triangle ABC, prove that : a (b cos C-c cos B) = b^2 -c^2 .

Using vectors, prove that cos(alpha-beta)=cosalpha cosbeta+sinalphasinbeta