Đáp án:
$\widehat{A} = 130^o$
$\widehat{B} = 80^o$
$\widehat{C} = 50^o$
$\widehat{D} = 100^o$
Giải thích các bước giải:
Ta có:
$\widehat{ADC} = \widehat{DEA} + \widehat{DAE} = 50^o + \widehat{DAE}$
$\widehat{ABC} = \widehat{CFA} + \widehat{CAF} = 30^o + \widehat{CAF}$
$\Rightarrow \widehat{ADC} + \widehat{ABC} = 80^o + \widehat{DAE} + \widehat{CAF}$
$\Leftrightarrow 180^o = 80^o + 2\widehat{CAF}$
$\Leftrightarrow \widehat{CAF} = 50^o$
$\Rightarrow \widehat{BCD} = 50^o$
$\Rightarrow \widehat{DAB} = 130^o$
$\Rightarrow \widehat{ABC} = 80^o$
$\Rightarrow \widehat{ADC} = 100^o$
