一到高一数学题 第二问
1个回答
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f(x)=tan(2x+π/4)
f(a/2)
=tan(a+π/4)
=(tana+1)/(1-tana)
=(sina+cosa)/(cosa-sina)
=2(cos²a-sin²a)
∴2(cosa-sina)²=1
∵a∈(0,π/4)
∴cosa>sina
∴cosa-sina=√2/2
√2cos(a+π/4)=√2/2
cos(a+π/4)=1/2
a+π/4=π/3
a=π/12
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f(a/2)
=tan(a+π/4)
=(tana+1)/(1-tana)
=(sina+cosa)/(cosa-sina)
=2(cos²a-sin²a)
∴2(cosa-sina)²=1
∵a∈(0,π/4)
∴cosa>sina
∴cosa-sina=√2/2
√2cos(a+π/4)=√2/2
cos(a+π/4)=1/2
a+π/4=π/3
a=π/12
如果你认可我的回答,请点击“采纳回答”,祝学习进步!
更多追问追答
追问
=tan(a+π/4)
=(tana+1)/(1-tana),我不明白这一步
追答
tan(a+π/4)
=(tana+tanπ/4)/(1-tanatanπ/4)
=(tana+1)/(1-tana)
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