Question

cos²B-cos²A/sinA. cosA+sinB.cosB=tan(a-b)​

Answer 1

Answer:

Step-by-step explanation:

cos²B-cos²A/sinA. cosA+sinB.cosB

= (Cos2A - Cos2B) / [2SinACosA + 2SinBCosB]

= (Cos2A - Cos2B) / (Sin2A + Sin2B)

= [2Sin(A+B)Sin(A-B)] /[2sin(A+B).cos(A-B)]

= Sin(A-B)/Cos(A-B)

= Tan(A-B)

= R.H.S

Hence proved.