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tanx=1/7,tany=1/3,且x,y都是锐角,则2x+y=
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tanx=1/7,tany=1/3,且x,y都是锐角,则2x+y=
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答案和解析
tanx = 1/7,tany = 1/3
tan2x = 2tanx/(1-(tanx)^2)
= (2/7) / (48/49)
= 7/24
tan( 2x+y)
= (tan2x + tany)/(1-tan2xtany)
= (7/24 + 1/3) /(1- (7/24)/3)
= (15/24)/ (65/72)
= (5/8)(72/65)
= 9/13
2x+y = arctan(9/13)
tan2x = 2tanx/(1-(tanx)^2)
= (2/7) / (48/49)
= 7/24
tan( 2x+y)
= (tan2x + tany)/(1-tan2xtany)
= (7/24 + 1/3) /(1- (7/24)/3)
= (15/24)/ (65/72)
= (5/8)(72/65)
= 9/13
2x+y = arctan(9/13)
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