Question

Answer 1

Lời giải:

$\widehat{A}=3\widehat{D}$

$\widehat{A}+\widehat{D}=180^0$ (hai góc trong cùng phía)

$\Rightarrow 3\widehat{D}+\widehat{D}=180^0$

$\Leftrightarrow 4\widehat{D}=180^0$

$\Leftrightarrow \widehat{D}=45^0$

$\widehat{A}=3\widehat{D}=135^0$

Mặt khác:

$\widehat{B}+\widehat{C}=180^0$ (hai góc trong cùng phía)

$\widehat{B}-\widehat{C}=30^0$

$\Rightarrow \widehat{B}=\frac{180^0+30^0}{2}=105^0$

$\widehat{C}=\widehat{B}-30^0=105^0-30^0=75^0$

Answer 2

Bài 2: