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若x+y+z=nπ,求证:tanx+tany+tanz=tanxtanytanz
人气:245 ℃ 时间:2020-06-18 18:28:06
解答
tan(x+y)=(tanx+tany)/(1-tanxtany)所以 tanx+tany=tan(x+y)(1-tanxtany)x+y+z=nπ所以 tanz=tan[nπ-(x+y)]=-tan(x+y)所以 tanx+tany+tanz=tan(x+y)(1-tanxtany)-tan(x+y)=-tan(x+y)tanxtany=tanxtanytanz得证...
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