$\angle \mathrm{EAD}=\angle \mathrm{AED}=\angle \mathrm{CAB}=\angle \mathrm{BCA}\phantom{\rule{0ex}{0ex}}\phantom{\rule{0ex}{0ex}}\mathrm{We}\mathrm{know}\mathrm{the}\mathrm{sum}\mathrm{of}\mathrm{the}2\mathrm{outside}\mathrm{angles}=180126=54\xb0\phantom{\rule{0ex}{0ex}}\phantom{\rule{0ex}{0ex}}\mathrm{Looking}\mathrm{at}\mathrm{the}\mathrm{biggest}\mathrm{triangle}\mathrm{AEC},\mathrm{let}3\mathrm{blue}\mathrm{angles}\mathrm{be}U\mathrm{each}\phantom{\rule{0ex}{0ex}}3U+54=180\xb0\phantom{\rule{0ex}{0ex}}U=126\xf73=42\xb0\left(\mathrm{ans}\right)\phantom{\rule{0ex}{0ex}}$ 


