Question

Найдите $27-10ctg alpha = ?, cos alpha = - frac {2}{ sqrt{6} } , и 90 ^{0} < alpha < 180 ^{0}$

Answer 1

cosa=-2/√6⇒sina=√1-4/6=√2/6=1/√3
ctga=cosa/sina=-2/√6 :1/√3=2√3/√6=-√2
27-10ctga=27-10*(-√2)=27+10√2