Soddalashtiring: 3α+α/3α-α

$\cos3\alpha+\cos\alpha=2\cos2\alpha\cos\alpha$ va $\sin3\alpha-\sin\alpha=2\cos2\alpha\sin\alpha$, nisbat $\frac{\cos\alpha}{\sin\alpha}=\mathrm{ctg}\,\alpha$.

Manba: UZBMB namunaviy test topshiriqlari (Milliy sertifikat, Matematika)