化简:(1)1-tanˆ2(x+y)/2tan(x+y) (2)sin4a/1+cos4a

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化简:(1)1-tanˆ2(x+y)/2tan(x+y) (2)sin4a/1+cos4a

化简:(1)1-tanˆ2(x+y)/2tan(x+y) (2)sin4a/1+cos4a
化简:(1)1-tanˆ2(x+y)/2tan(x+y) (2)sin4a/1+cos4a

化简:(1)1-tanˆ2(x+y)/2tan(x+y) (2)sin4a/1+cos4a
1)
=1/[2tan(x+y)/1-tan²(x+y)]
=1/[tan2(x+y)]
2)
=2sin2acos2a/(2cos²2a-1+1)
=sina2a/cos2a
=tan2a