For every possible angle [tex]x [/tex], the fundamental law of trigonometric states that
[tex] \sin^2(x)+\cos^2(x) = 1 [/tex]
In your case, the inputs you provided would lead to
[tex] \dfrac{16}{25}+\dfrac{25}{169} = \dfrac{3329}{4225} \approx 0.8 \neq 1 [/tex]
So, it is not possible that, for a certain angle x, we have
[tex]\sin(x) = \dfrac{4}{5},\quad \cos(x) = -\dfrac{5}{13} [/tex]
