cos(pi+x)=1/2

Разделим обе части ур-ния на -1

Ур-ние превратится в
$$cos{left (x right )} = – frac{1}{2}$$
Это ур-ние преобразуется в
$$x = pi n + {acos}{left (- frac{1}{2} right )}$$
$$x = pi n – pi + {acos}{left (- frac{1}{2} right )}$$
Или
$$x = pi n + frac{2 pi}{3}$$
$$x = pi n – frac{pi}{3}$$
, где n – любое целое число

2*pi
x1 = —-
3

4*pi
x2 = —-
3

x1 = -67.0206432766000

x2 = 630.412925820000

x3 = -14.6607657168000

x4 = -1623.15620435000

x5 = -20.9439510239000

x6 = -16.7551608191000

x7 = 29.3215314335000

x8 = 98.4365698125000

x9 = -10.4719755120000

x10 = 71.2094334814000

x11 = -8.37758040957000

x12 = 48.1710873550000

x13 = 58.6430628670000

x14 = 416.784625376000

x15 = 10.4719755120000

x16 = 20.9439510239000

x17 = -29.3215314335000

x18 = 27.2271363311000

x19 = -60.7374579694000

x20 = 14.6607657168000

x21 = 23.0383461263000

x22 = -83.7758040957000

x23 = -41.8879020479000

x24 = -64.9262481742000

x25 = -71.2094334814000

x26 = 60.7374579694000

x27 = -77.4926187885000

x28 = 117.286125734000

x29 = 8.37758040957000

x30 = 92.1533845053000

x31 = 2.09439510239000

x32 = 35.6047167407000

x33 = -79.5870138909000

x34 = -85.8701991981000

x35 = 4.18879020479000

x36 = 67.0206432766000

x37 = 54.4542726622000

x38 = 46.0766922527000

x39 = -2.09439510239000

x40 = 41.8879020479000

x41 = -27.2271363311000

x42 = 90.0589894029000

x43 = -33.5103216383000

x44 = -52.3598775598000

x45 = 39.7935069455000

x46 = -73.3038285838000

x47 = -23.0383461263000

x48 = 77.4926187885000

x49 = -96.3421747101000

x50 = 73.3038285838000

x51 = -48.1710873550000

x52 = 64.9262481742000

x53 = -92.1533845053000

x54 = -46.0766922527000

x55 = -35.6047167407000

x56 = 79.5870138909000

x57 = 85.8701991981000

x58 = 96.3421747101000

x59 = -98.4365698125000

x60 = -39.7935069455000

x61 = -54.4542726622000

x62 = 83.7758040957000

x63 = 16.7551608191000

x64 = 33.5103216383000

x65 = -90.0589894029000

x66 = -58.6430628670000

x67 = -4.18879020479000

x68 = 52.3598775598000