## Thinking Mathematically (6th Edition)

$m\angle{HAF} = 50^o$ The angle is acute.
point H is at $180^o$ point F is at $130^o$ Thus, $m\angle{HAF} =180^o-130^o=50^o$ Acute angles are angles whose measure is less than 90 degrees. Thus, $\angle{HAF}$ is acute.