Question

cos^2(a) + ctg^2(a) + sin^2 (a) при а= п/6​

Answer 1

$\displaystyle cos^2a+ctg^2a+sin^2a=1+ctg^2a=\frac{1}{sin^2a}=\frac{1}{sin^2\frac{\pi}{6}}=\frac{1}{\frac{1}{4}}=4$