Question

Решите, ответ округлите до десятых
cos(arccos0,9)+arccos(cos4π/4)+arccos(−√3/2)

Answer 1

$cos(arccos(0,9))+arccos(cos( \frac{4\pi}{4} ))+arccos(-\frac{ \sqrt{3} }{2} )\\cos(arccos(x))=x\\0,9+arccos(cos(\pi)+\frac{5\pi}{6} =0,9+\pi+\frac{5\pi}{6} =\\=\frac{9}{10} +\frac{11\pi}{6} \\\frac{11*3,14}{6} =\frac{\frac{1727}{50} }{6} =5\frac{227}{300} =5,75\\0,9+5,75=6,65$