Question

Giúp mình với

Answer 1

Giải:
a) Xét \(\Delta ADC,\Delta ABC\) có:
\(AD=AB\left(gt\right)\)

\(\widehat{A_1}=\widehat{A_2}=90^o\)

\(AC\): cạnh chung

\(\Rightarrow\Delta ADC=\Delta ABC\left(c-g-c\right)\left(đpcm\right)\)

b) Vì \(\Delta ADC=\Delta ABC\)

\(\Rightarrow\widehat{DAC}=\widehat{BCA}\) ( góc t/ứng )

Ta có: \(\widehat{ADC}+\widehat{DAC}=90^o\) ( do \(\Delta ADC\) có \(\widehat{A_2}=90^o\) )

\(\Rightarrow\widehat{ADC}+\widehat{BCA}=90^o\left(đpcm\right)\)