So sánh hai góc $\widehat {CAC'};\,\widehat {CBC'}$?

${60^ \circ }$

${70^ \circ }$

${90^ \circ }$           

${120^ \circ }$

$\Delta BAD = \Delta HIK$           

$\Delta ABD = \Delta KHI$

$\Delta DAB = \Delta HIK$           

$\Delta ABD = \Delta KIH$

$\Delta BAD = \Delta HIK$           

$\Delta ABD = \Delta KHI$

$\Delta DAB = \Delta HIK$           

$\Delta ABD = \Delta KIH$

$\widehat {BCA} = \widehat {BAC'}$

$\Delta ACB = \Delta BAC'$

$\widehat {BCA} = \widehat {ABC'}$       

$\Delta ACB = \Delta BC'A$

$\widehat {BCA} = \widehat {BAC'}$

$\Delta ACB = \Delta BAC'$

$\widehat {BCA} = \widehat {ABC'}$       

$\Delta ACB = \Delta BC'A$

$\Delta ABC = \Delta ACD$ 

$\Delta ABC = \Delta CDA$   

$\Delta ABC = \Delta ADC$ 

$\Delta ABC = \Delta CAD$