tan^2a=2tan^2⊙+1求证sin^2⊙=2sin^2a-1

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tan^2a=2tan^2⊙+1求证sin^2⊙=2sin^2a-1tan^2a=2tan^2⊙+1求证sin^2⊙=2sin^2a-1tan^2a=2tan^2⊙+1求证sin^2⊙=2sin^2a

tan^2a=2tan^2⊙+1求证sin^2⊙=2sin^2a-1
tan^2a=2tan^2⊙+1求证sin^2⊙=2sin^2a-1

tan^2a=2tan^2⊙+1求证sin^2⊙=2sin^2a-1
tan^2a=2tan^2⊙+1
sin^2a/(1-sin^2a)=2sin^2⊙/(1-sin^2⊙)+1
sin^2a/(1-sin^2a+sin^2a)
=(sin^2⊙+1)/(1-sin^2⊙+sin^2⊙+1)
sin^2a=(sin^2⊙+1)/2
所以:
sin^2⊙=2sin^2a-1