\(\displaystyle{ 1-cosx+\frac{1}{cosx}}\)
Podstawiajac do wzoru na sume cos otrzymuje :
\(\displaystyle{ \frac{2cos{\frac{x+90-x}{2}}cos{\frac{x-90+x}{x}}+cos2\Pi}{cosx}}\)
\(\displaystyle{ \frac{2cos(\frac{\Pi}{4})cos({\frac{x}{2}}-{\frac{\Pi}{4}})+cos2\Pi}{cosx}}\)
a ma byc:
\(\displaystyle{ \frac{2\sqrt{2}cos(\frac{\Pi}{4})cos({\frac{x}{2}}-{\frac{\Pi}{4}})}{cosx}}\)
czyli trzeba cos zrobic z cos2Π ,ale co?