Question

Помогите с тригонометрией $(ctg(arccos \frac{1}{8} ))^{-2}$
Вычислите

Answer 1

сtg(arccosx)=x/√(1-x²)
ctg(arccos1/8)=1/8:√(1-1/64)=1/8:√63/64=1/8:3√7/8=1/8*8/3√7=1/3√7
(ctg(arcos1/8))^-1=(1/3√7)^-1=3√7