Задание

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На рисунке \(a\parallel b\) , \(c\) — секущая, \(\angle 4 + \angle 6 = 78\degree\) . Найди все углы, обозначенные цифрами.

Решение.

  1. По условию \(\angle 4 + \angle 6 = 78\degree\) , а эти углы [ ], поэтому \(\angle 4 \) [ ] \(\angle 6 =\) [ ] \(\degree\) .

  2. \(\angle 2 = \angle 4\) , \(\angle 8 = \angle 6\) , так как эти углы [ ], поэтому \(\angle 2 = \) [ ] \(\degree\) и \(\angle 8 =\) [ ] \(\degree\) .

  3. \(\angle 3 =\) [ ] \(\degree - \angle 4 =\) [ ] \(\degree\) , \(\angle 5 =\) [ ] \(\degree - \angle 6 = \) [ ] \(\degree\) , так как \(\angle 3\) и \(\angle 4\) , \(\angle 5\) и \(\angle 6\) — [ ].

  4. \(\angle 1 = \angle 3\) и \(\angle 7 = \angle 5\) , так как эти углы [ ].

Ответ: \(\angle 1=\) [ ] \(\degree\) , \(\angle 2=\) [ ] \(\degree\) , \(\angle 3=\) [ ] \(\degree\) , \(\angle 4=\) [ ] \(\degree\) , \(\angle 5=\) [ ] \(\degree\) , \(\angle 6=\) [ ] \(\degree\) , \(\angle 7=\) [ ] \(\degree\) , \(\angle 8=\) [ ] \(\degree\) .