If theta is an acute angle and sintheta=1/2, then what is costheta?

Jan 3, 2017

$\frac{\sqrt{3}}{3}$
${\cos}^{2} a + {\sin}^{2} a = 1$
${\cos}^{2} t = 1 - {\sin}^{2} t = 1 - \frac{1}{4} = \frac{3}{4}$
$\cos t = \pm \frac{1}{\sqrt{3}} = \pm \frac{\sqrt{3}}{3}$
$\cos t = \frac{\sqrt{3}}{3}$