## Elementary Geometry for College Students (5th Edition)

$\angle$ADB=153$^{\circ}$
Given: A roof truss with AB=8 and $\angle$HAF=37$^{\circ}$ also $\angle$ABD=90$^{\circ}$ as we all know in a roof truss opposite triangles are always congruent that means $\triangle$ABD is congruent to $\triangle$AFH therefore, $\angle$HAF=$\angle$BAD=37$^{\circ}$ now we have to find m$\angle$ADB so m$\angle$BAD+$\angle$ADB+$\angle$ABD=180$^{\circ}$ 37+$\angle$ADB+90=180 $\angle$ADB+127=180 $\angle$ADB=180-127 $\angle$ADB=153$^{\circ}$