Hi ╔(σ_σ)╝!
(have a theta: θ and a phi: φ )
Quote by ╔(σ_σ)╝
… I found that
P dot Q = cos([tex]\phi[/tex]  [tex]\theta[/tex])
But the answer at the back of my book says
cos([tex]\phi[/tex])cos( [tex]\theta[/tex])  sin([tex]\phi[/tex])sin( [tex]\theta[/tex])
I guess this is the same P dot Q, so my answer is the same as the book.

If that's meant to be cos(θ  φ), then the book is wrong.
3) … So P  Q/2 = 1cos[tex]\varphi[/tex]
Right ?
But then my book says the answer is sin (0.5([tex]\phi[/tex]  [tex]\theta[/tex]))

i] A is the
squareroot of A.A
ii] 1 + cos2θ = 2sin
^{2}θ