Question

cos x/3 = 1/√2 срочно

Answer 1

$cos frac{x}{3} = frac{1}{ sqrt{2} }$
⇒$frac{1}{ sqrt{2} } = frac{1}{ sqrt{2} } *1= frac{1}{ sqrt{2} } * frac{ sqrt{2} }{ sqrt{2} }= frac{ sqrt{2} }{2}$
⇒$frac{x}{3} =+-arccos frac{ sqrt{2} }{2} +2 pi k$
⇒$frac{x}{3} =+- frac{ pi }{4}+2 pi k$
⇒$x=+- frac{3* pi }{4} + 6 pi *k;$ k∈Z

Answer 2

ошибься

Answer 3

исправил

Answer 4

cos (x/3)= √2/2
x1/3= π/4+2πk1        k1∈z
x1= 3π/4 +6πk1       k1∈z

x2/3= 7π/4+ 2πk2     k2∈z
x2= 21π/4 +6πk2       k2∈z