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HW Helper
Thanks
P: 26,167
Hi ╔(σ_σ)╝!

(have a theta: θ and a phi: φ )
 Quote by ╔(σ_σ)╝ … I found that P dot Q = cos($$\phi$$ - $$\theta$$) But the answer at the back of my book says cos($$\phi$$)cos( $$\theta$$) - sin($$\phi$$)sin( $$\theta$$) 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 = 1-cos$$\varphi$$ Right ? But then my book says the answer is |sin (0.5($$\phi$$ - $$\theta$$))|
i] |A| is the square-root of A.A

ii] 1 + cos2θ = 2sin2θ