if sin a, sin b, sin c are in A.P.and cos a, cos b, cos c are in G.P., then the value of (cos^2a + cos^2b – 4cosa cosb) / (1- sina sinb) =

Hello student, Please find the answer to your question below

(cos^2a + cos^2b – 4cosa cosb) / (1- sina sinb)

sin a, sin b, sin c…... So, 2 sinb = sin a + sin c…..(1)
cos a, cos b, cos c …..So, cos²b = Cosa* cosc….…..(2)

Now you can use this in the question