If `cosx= tany, cosy= tanz and cosz= tanx`, prove that `sinx= siny= sinz = sin18^@`

If cosx=tany,cosy=tanz and cosz=tanx , then sin^2x=?

If cos x=tany, cos y=tanz and cos z = tanx , then sinx = 2sin theta where theta is (where, x,y, z, theta are acuate angles)

If sinx+siny = a, cosx+cosy = b, prove that sin(x+y) = (2ab)/(a^(2)+b^(2))

If cosx + cosy + cosz = 0 = sinx + siny + sinz ,then possible value of cos((x-y)/2) is (A) 4 3 1 2 (B) 4 3 2 1 (C) 3 4 2 1 (D) 3 4 1 2

If cosx.cosy + sinx.siny = -1 then cosx + cosy is

If cos x. cosy+sinx.siny=-1 then cosx+cosy is :