Question

Вычислите: sin$13pi/6$; cos(405); tg($-11pi/6$) ; ctg $5pi/4$

Answer 1

$sinfrac{13pi}{6}=sin(2pi +frac{pi}{6})=sinfrac{pi}{6}=frac{1}{2}\\cos405^0=cos(360^0+45^0)=cos45^0=frac{sqrt2}{2}\\tg(-frac{11pi}{6})=-tg(2pi -frac{pi}{6})=-tg(-frac{pi}{6})=tgfrac{pi}{6}=frac{sqrt3}{3}\\ctgfrac{5pi}{4}=ctg(pi +frac{pi}{4})=ctgfrac{pi}{4}=1$