Explicație pas cu pas:
1)
[tex] \sin(x) = \frac{3}{5} \\ \sin^{2} (x ) + \cos^{2} (x) = 1 \\ \cos^{2} (x) = 1 - {( \frac{3}{5}) }^{2}= 1 - \frac{9}{25}=\frac{16}{25}\\ \cos(x)=\sqrt{ {( \frac{4}{5} )}^{2} }\\0 \leqslant x \leqslant \frac{\pi}{2} = > cos(x) = \frac{4}{5} [/tex]
2)
[tex] \sin(x) = \frac{3}{5} \\ \sin^{2} (x ) + \cos^{2} (x) = 1 \\ \cos^{2} (x) = 1 - {( \frac{3}{5}) }^{2} = 1 - \frac{9}{25} = \frac{16}{25} \\ \cos(x) = \sqrt{ {( \frac{4}{5} )}^{2} } \\ \frac{\pi}{2} \leqslant x \leqslant \pi= > cos(x) = - \frac{4}{5} [/tex]
