MATH HELP!!

A(1,-2)繞原點按逆時針方向旋轉90度後再沿直線y=-1反射。求所得的影像的坐標。
繞原點按逆時針方向旋轉90度後坐標=(2,1)
再沿直線y=-1反射後坐標=(2,-3)
所以所得的影像的坐標=(2,-3)
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((1/sinx) - sinx)/cosx
=[(1-sin^2 x)/sinx]/cosx
=cos^2 x/sinxcosx
=cosx/sinx
=1/tanx

((1/sinx) - sinx)/cosx=A(-1,-2)

=A(-1,-2)