# How do you find the cos of theta if sin of theta=1/4 and 0<theta<pi/2?

Jul 22, 2016

$\cos t = \frac{\sqrt{15}}{4}$
$\sin t = \frac{1}{4}$ . Find cos t
Use trig identity: ${\cos}^{2} t = 1 - {\sin}^{2} t$
${\cos}^{2} t = 1 - \frac{1}{16} = \frac{15}{16}$
$\cos t = \pm \frac{\sqrt{15}}{4}$
$\cos t = \frac{\sqrt{15}}{4}$