sin\alpha=\frac{1}{cos\alpha}
sin\alpha+cos\alpha=x |^2
x^2=(sin\alpha+cos\alpha)^2
x^2=sin^2\alpha+2\sin\alpha cos \alpha+cos^2\alpha
x^2=1+2sin\alpha cos\alpha
x^2=1+2\cdot \frac{1}{cos\alpha}\cdot cos\alpha
x^2=1+2
x^2=3
x=-\sqrt3 \vee x=\sqrt3
sin\alpha+cos \alpha = \mp \sqrt3 <-- odpowiedź