Step-by-step explanation:
[tex] \sin(θ) = \frac{2}{5} [/tex]
We know that
[tex] { \sin ^{2} (θ) } + \cos^{2} (θ) = 1[/tex]
Using that we get
[tex] \cos^{2} (θ) = 1 - \sin^{2}( θ) = 1 - { \frac{2}{5} }^{2} [/tex]
[tex] = 1 - \frac{4}{25} [/tex]
[tex] \frac{21}{25} [/tex]
hence
[tex] \cos(θ ) = \frac{ \sqrt{21} }{5} [/tex]
