Question

Срочно надооо пж... ​

Answer 1

$ctg(arcctg(-2,5))+tg(arctg3)+arcctg(tg\frac{3\pi}{9})=\\\\=-2,5+3+arcctg\Big(tg(\frac{\pi}{2}-\frac{\pi}{6})\Big)=\\\\=0,5+arcctg(ctg\frac{\pi}{3})=0,5+\frac{\pi}{3}\approx 0,5+1,05=1,55$