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Ask iit jee aieee pet cbse icse state board community Discussion Response Post to: rates assured eliminate theta
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hsbhatt (4460)

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Olaaa!! Perrrfect answer. 840  [970 rates]

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cos  + cos2   = p
sin   + sin2     = q   
 
Squaring and adding the equations, we get
p2+q2 = 2+2(cos cos2+sin sin2) = 2+2cos
 
Hence cos = p2+q2/2 - 1
 
Let p2+q2 = 2m
 
Hence cos = m-1
 
cos2 = 2(m-1)2 - 1 = 2m2 -4m+1
 
From eqn 1,
cos  + cos2   = p
 
Hence 2m2-3m = p where m = p2+q2/2 thus eliminating
 
sorry sboosy, I didnt know you were on to this one!

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