Question

if sin theta=a/b,find the value ofcos theta

Answer 1

$\sin \: theta = \frac{a}{b} \\ \\ \cos \: theta = \sqrt{1 - { \sin}^{2}theta } \\ \\ \cos \: theta = \sqrt{1 - (\frac{a}{b} )^{2} } \\ \\ \cos \: theta = \sqrt{1 - \frac{a ^{2} }{b^{2} } }$


As we know,

$\sin^{2} theta + \cos^{2} theta = 1$

Hope it will help you