If cosxcosy= cosθ, prove that:

sin^2 (x/2) cos^2 (y/2) +cos^2 (x/2) sin^2 (y/2) = sin^2 (θ/2)

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- Mar 8th 2010, 09:13 AMyobaculTrigonometric Proof
If cos

*x*cos*y*= cos*θ*, prove that:

sin^2 (*x*/2) cos^2 (*y*/2) +cos^2 (*x*/2) sin^2 (*y*/2) = sin^2 (*θ*/2)

- Mar 8th 2010, 12:47 PMOpalg
- Mar 8th 2010, 10:07 PMyobaculNope ...
(Worried)

I tried to .... I managed to get what I required on the RHS but I didn't manage to rearrange the rest to get the LHS. - Mar 10th 2010, 05:58 AMOpalg