## Thinking Mathematically (6th Edition)

$m\angle{CAB} = 20^o$ $\angle{CAB}$ is acute.
point C is at $0^o$ point B is at $20^o$ Thus, $m\angle{CAB} =20^o$ Acute angles are angles whose measure is less than 90 degrees. Thus, $\angle{CAB}$ is acute.