(2)sinx/1-cosx=1+cosx/sinx ( /后是分母)
请写清解题过程 谢谢!
sin4α-cos4α=2sin(2α)*cos(2α)-(1-2*sin(2α)^2)=2sin(2α)*cos(2α)+2*sin(2α)^2-1
=2*sin(2α)(cos(2α)+sin(2α))-1
cos(2α)+sin(2α)不恒于1
sin4α-cos4α=2sin2α-1 不是恒等圆升式
sinx/1-cosx=1+cosx/烂配sinx 不是恒等橘历老式
证明下列恒等式：
(1)sin4α-cos4α=2sin2α-1
(2)sinx/1-cosx=1+cosx/sinx ( /后是分母)
请写清解题过程 谢谢!
sin4α-cos4α=2sin(2α)*cos(2α)-(1-2*sin(2α)^2)=2sin(2α)*cos(2α)+2*sin(2α)^2-1
=2*sin(2α)(cos(2α)+sin(2α))-1
cos(2α)+sin(2α)不恒于1
sin4α-cos4α=2sin2α-1 不是恒等圆升式
sinx/1-cosx=1+cosx/烂配sinx 不是恒等橘历老式
(2)sinx/1-cosx=1+cosx/sinx ( /后是分母)
请写清解题过程 谢谢!
sin4α-cos4α=2sin(2α)*cos(2α)-(1-2*sin(2α)^2)=2sin(2α)*cos(2α)+2*sin(2α)^2-1
=2*sin(2α)(cos(2α)+sin(2α))-1
cos(2α)+sin(2α)不恒于1
sin4α-cos4α=2sin2α-1 不是恒等圆升式
sinx/1-cosx=1+cosx/烂配sinx 不是恒等橘历老式