Question Number 166134 by amin96 last updated on 13/Feb/22
Answered by MJS_new last updated on 14/Feb/22
$$\mathrm{you}\:\mathrm{need}\:\mathrm{the}\:\mathrm{trigonometric}\:\mathrm{method}\:\mathrm{to}\:\mathrm{get} \\ $$$${x}_{\mathrm{1}} =−\mathrm{cos}\:\frac{\pi}{\mathrm{9}} \\ $$$${x}_{\mathrm{2}} =\mathrm{sin}\:\frac{\pi}{\mathrm{18}} \\ $$$${x}_{\mathrm{3}} =\mathrm{cos}\:\frac{\mathrm{2}\pi}{\mathrm{9}} \\ $$