作业帮一道函数题!求帮助
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一道函数题!求帮助
一道函数题!求帮助
一道函数题!求帮助
tan²a=2tan²β+1那么等式左右两边同时加1
则tan²a+1=2tan²β+2 等式变为1/cos²a=2/cos²β,得到cos²β=2cos²a
则2-cos²β=2-2cos²a
为1+sin²β=2sin²a
tan^2A=2tan^B+1
(sinA/cosA)^2=2(sinB/cosB)^2+1
sin^2A/cos^2A=2sin^2B/cos^2B+1
sin^2A*cos^2B=2sin^2Bcos^2A+cos^2Acos^2B
sin^2A(1-sin^2B)=2sin^2B(1-sin^2A)+(1-sin^2A)(1-sin^2B)
sin^2A-sin^2Asin^2B=2sin^2B-2sin^2Asin^2B+1-sin^2A-sin^2B+sin^2Asn^2B
sin^2B=2sin^2A-1