If $\sin \theta =\frac{2}{5}$  then find the value of $\cos \theta \text{ and }\tan \theta .$

• A

  $\cos \theta =\frac{\sqrt{22}}{5},\tan \theta =\frac{2}{\sqrt{22}}$

• B

  $\cos \theta =\frac{\sqrt{21}}{5},\tan \theta =\frac{2}{\sqrt{21}}$

• C

  $\cos \theta =1,\tan \theta =\frac{2}{\sqrt{21}}$

• D

  $\cos \theta =\frac{\sqrt{21}}{5},\tan \theta =1$