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If `tan(alpha+theta)=ntan(alpha-theta)`, show that `(n+1)sin2theta=(n-1)sin2alphadot` |
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Answer» `tan(alpha+theta) = n tan(alpha-theta)` `=>tan(alpha+theta)/(tan(alpha-theta)) = n/1` Using componendo and dividendo, `=>(tan(alpha+theta)+tan(alpha-theta))/(tan(alpha+theta)-tan(alpha-theta)) = (n+1)/(n-1)` `=>(sin(alpha+theta)/cos(alpha+theta)+sin(alpha-theta)/cos(alpha-theta))/(sin(alpha+theta)/cos(alpha+theta)-sin(alpha-theta)/cos(alpha-theta)) = (n+1)/(n-1)` `=>(sin(alpha+theta)cos(alpha-theta)+cos(alpha+theta)sin(alpha-theta))/(sin(alpha+theta)cos(alpha-theta)+cos(alpha+theta)sin(alpha-theta)) =(n+1)/(n-1)` `=>(sin(alpha+theta+alpha-theta))/(sin(alpha+theta-alpha+theta))=(n+1)/(n-1)` `=>(sin2alpha)/(sin2theta) = (n+1)/(n-1)` `=>(n-1)sin2alpha = (n+1)sin2theta.` |
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