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.
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If that's meant to be cos(θ - φ), then the book is wrong.
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3) … So |P - Q|/2 = 1-cos[tex]\varphi[/tex]
Right ?
But then my book says the answer is |sin (0.5([tex]\phi[/tex] - [tex]\theta[/tex]))|
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i] |A| is the
square-root of A.A
ii] 1 + cos2θ = 2sin
2θ