已知∶(sinx)^4/a²+﹙cosx﹚^ 4/b²=1/﹙a²﹢b²﹚求出∶﹙sinx﹚^2008/a^2006+﹙cosx﹚^2008/b^2006的值
来源:学生作业帮助网 编辑:作业帮 时间:2024/07/13 05:05:47
![已知∶(sinx)^4/a²+﹙cosx﹚^ 4/b²=1/﹙a²﹢b²﹚求出∶﹙sinx﹚^2008/a^2006+﹙cosx﹚^2008/b^2006的值](/uploads/image/z/8636359-31-9.jpg?t=%E5%B7%B2%E7%9F%A5%E2%88%B6%28sinx%29%5E4%EF%BC%8Fa%26%23178%3B%EF%BC%8B%EF%B9%99cosx%EF%B9%9A%5E+4%EF%BC%8Fb%26%23178%3B%EF%BC%9D1%EF%BC%8F%EF%B9%99a%26%23178%3B%EF%B9%A2b%26%23178%3B%EF%B9%9A%E6%B1%82%E5%87%BA%E2%88%B6%EF%B9%99sinx%EF%B9%9A%5E2008%EF%BC%8Fa%5E2006%EF%BC%8B%EF%B9%99cosx%EF%B9%9A%5E2008%EF%BC%8Fb%5E2006%E7%9A%84%E5%80%BC)
已知∶(sinx)^4/a²+﹙cosx﹚^ 4/b²=1/﹙a²﹢b²﹚求出∶﹙sinx﹚^2008/a^2006+﹙cosx﹚^2008/b^2006的值
已知∶(sinx)^4/a²+﹙cosx﹚^ 4/b²=1/﹙a²﹢b²﹚
求出∶﹙sinx﹚^2008/a^2006+﹙cosx﹚^2008/b^2006的值
已知∶(sinx)^4/a²+﹙cosx﹚^ 4/b²=1/﹙a²﹢b²﹚求出∶﹙sinx﹚^2008/a^2006+﹙cosx﹚^2008/b^2006的值
(sinx)^4/a²+﹙cosx﹚^ 4/b²=1/﹙a²﹢b²﹚
(b^2sinx^4+a^2cosx^4)/a^2b^2=1/(a^2+b^2)
a^2b^2sinx^4+b^4sinx^4+a^4cos^4+a^2b^2cosx^4=a^2b^2
a^2b^2sinx^4+b^4sinx^4+a^4cos^4+a^2b^2(1-sinx^2)^2=a^2b^2
a^2b^2sinx^4+b^4sinx^4+a^4cos^4+a^2b^2(1-2sinx^2+sinx^4)-a^2b^2=0
b^4sinx^4+a^4cos^4-2a^2b^2sinx^2(1-sinx^2)=0
(b^2sinx^2-a^2cosx^2)^2=0
b^2sinx^2=a^2cosx^2
sinx^2/a^2=cos^2/b^2
∴﹙sinx﹚^2008/a^2006+﹙cosx﹚^2008/b^2006
=sinx^2006*sinx^2/a^2006+﹙cosx﹚^2008/b^2006
=cosx^2006*(1-cosx^2)/b^2006+cosx^2008/b^2006
=cosx^2006/b^2006
又sinx^4/a^2+cosx^4/b^2=1/(a^2+b^2)
sinx^2(1-cos^2)/a^2+cosx^4/b^2=1/(a^2+b^2)
cosx^2(1-cos^2)/b^2+cosx^4/b^2=1/(a^2+b^2)
cosx^2/b^2=1/(a^2+b^2)
∴﹙sinx﹚^2008/a^2006+﹙cosx﹚^2008/b^2006
=(cosx^2/b^2)^1003
=1/(a^2+b^2)^1003
好吧,楼上的已经把答案写的很详细了。