\(a,\widehat{x'Oy'}=\widehat{xOy}=70^0\left(2.góc.đđ\right)\)
\(b,\widehat{x'Oy}.đối.đỉnh.\widehat{xOy'}\) do \(Ox.đối.Ox';Oy.đối.Oy'\)
\(c,\widehat{xOy'}+\widehat{xOy}=180^0\left(kề.bù\right)\\ \Rightarrow\widehat{xOy'}=180^0-70^0=110^0\\ \widehat{xOy'}=\widehat{x'Oy}=110^0\left(đối.đỉnh\right)\)