x∈(π/2; π), reprezinta cadranul II, unde numai sinusul este pozitiv, deci:
sinx=[tex] \sqrt{1-cos^2x}= \sqrt{1- \frac{9}{49} }= \sqrt{ \frac{40}{49} }= \frac{2 \sqrt{10} }{7} [/tex], tgx=[tex] \frac{sinx}{cosx}= \frac{ \frac{2 \sqrt{10} }{7} }{- \frac{3}{7} }=- \frac{2 \sqrt{10} }{3},iar,ctg= \frac{1}{tgx}= -\frac{3}{2 \sqrt{10} } =- \frac{3 \sqrt{10} }{20} [/tex]
