#564 Помогите, пожалуйста

[latex]sinx=\frac{7}{25},\; \; \frac{\pi}{2}\ \textless \ x\ \textless \ \pi \\\\sint=\frac{11}{61}\; ,\; \; 0\ \textless \ t\ \textless \ \frac{\pi}{2}\\\\cos^2 \alpha =1-sin^2 \alpha \; \; \to \; \; cos \alpha =\pm \sqrt{1-sin^2 \alpha }\\\\cosx\ \textless \ 0,\; t.k.\; \; \frac{\pi}{2}\ \textless \ x\ \textless \ \pi \; \; \to \; \; cosx=-\sqrt{1-\frac{49}{625}}=-\sqrt{\frac{576}{625}}=-\frac{24}{25}\\\\cost\ \textgreater \ 0,\; t.k. \; 0\ \textless \ t\ \textless \ \frac{\pi}{2}\; \to \; cost=+\sqrt{1-\frac{121}{3721}}=\sqrt{\frac{3600}{3721}}=\frac{60}{61}[/latex] [latex]sin(x+t)=sinx\cdot cost+sint\cdot cosx=\frac{7}{25}\cdot \frac{60}{61} + \frac{11}{61} \cdot \frac{-24}{25} = \frac{156}{1525} \\\\sin(x-t)=sinx\cdot cost-cosx\cdot sint= \frac{7}{25} \cdot \frac{60}{61} - \frac{-24}{25} \cdot \frac{11}{61} = \frac{264}{1525} \\\\cos(x+t)=cosx\cdot cost-sinx \cdot sint= \frac{-24}{25} \cdot \frac{60}{61} - \frac{7}{25} \cdot \frac{11}{61} = \frac{-1517}{1525} [/latex]  [latex]cos(x-t)=cosx\cdot cost+sinx\cdot sixt= \frac{-24}{25} \cdot \frac{60}{61} + \frac{7}{25} \cdot \frac{11}{61} = [/latex] [latex] \frac{-1363}{1525} [/latex]