有关两角和与差的正弦余公式的题
sin(x+y)cos(z-y)-cos(y+x)sin(y-z)sin(x-y)sin(y-z)-cos(x-y)cos(z-y)...
sin(x+y)cos(z-y)-cos(y+x)sin(y-z)
sin(x-y)sin(y-z)-cos(x-y)cos(z-y) 展开
sin(x-y)sin(y-z)-cos(x-y)cos(z-y) 展开
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sin(x+y)cos(z-y)-cos(y+x)sin(y-z)
=sin(x+y)cos(y-z)-cos(x+y)sin(y-z)
=sin[(x+y)-(y-z)]
=sin(x+z)
sin(x-y)sin(y-z)-cos(x-y)cos(z-y)
=sin(x-y)sin(y-z)-cos(x-y)cos(y-z)
=-[cos(x-y)cos(y-z)-sin(x-y)sin(y-z)]
=-cos[(x-y)+(y-z)]
=-cos(x-z)
=sin(x+y)cos(y-z)-cos(x+y)sin(y-z)
=sin[(x+y)-(y-z)]
=sin(x+z)
sin(x-y)sin(y-z)-cos(x-y)cos(z-y)
=sin(x-y)sin(y-z)-cos(x-y)cos(y-z)
=-[cos(x-y)cos(y-z)-sin(x-y)sin(y-z)]
=-cos[(x-y)+(y-z)]
=-cos(x-z)
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