😃13.1 極坐標

https://www.geogebra.org/m/geZ4hED6#material/Hw75CHct

https://www.geogebra.org/m/kqyya2aa

練習

https://www.geogebra.org/m/yybw8rbv

https://www.geogebra.org/m/n5mvvtk2