Verified answer

arcsin1/2=π/6

3/π arcsin1/2=3/π * arcsin1/2=3/π *π/6=1/2

cos2x=1/2

2x=(-1)^n *arcsin1/2+πn,

2x=(-1)^n *π/6+πn,

x=(-1)^n*π/12+πn/2, n∈Z

n=0, x=π/12

n=1, x=-π/12+π/2=5π/12

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n=-1, x=-π/12-π/2=-7π/12,

Наименьшее положительное х=π/12