2*cos(x)+sqrt(2)=0

Перенесём sqrt(2) в правую часть ур-ния

с изменением знака при sqrt(2)

Получим:
$$2 cos{left (x right )} = – sqrt{2}$$

Разделим обе части ур-ния на 2

Ур-ние превратится в
$$cos{left (x right )} = – frac{sqrt{2}}{2}$$
Это ур-ние преобразуется в
$$x = pi n + {acos}{left (- frac{sqrt{2}}{2} right )}$$
$$x = pi n – pi + {acos}{left (- frac{sqrt{2}}{2} right )}$$
Или
$$x = pi n + frac{3 pi}{4}$$
$$x = pi n – frac{pi}{4}$$
, где n – любое целое число

3*pi
x1 = —-
4

5*pi
x2 = —-
4

x1 = 73.0420291960000

x2 = -77.7544181763000

x3 = -33.7721210261000

x4 = 21.2057504117000

x5 = 90.3207887907000

x6 = 10.2101761242000

x7 = 255.254403104000

x8 = 85.6083998103000

x9 = 22.7765467385000

x10 = 96.6039740979000

x11 = -66.7588438888000

x12 = 77.7544181763000

x13 = -85.6083998103000

x14 = -335.365015771000

x15 = 33.7721210261000

x16 = 29.0597320457000

x17 = 66.7588438888000

x18 = -60.4756585816000

x19 = -71.4712328692000

x20 = -16.4933614313000

x21 = -2.35619449019000

x22 = 71.4712328692000

x23 = -10.2101761242000

x24 = 3.92699081699000

x25 = 60.4756585816000

x26 = -54.1924732744000

x27 = 35.3429173529000

x28 = -29.0597320457000

x29 = 79.3252145031000

x30 = -47.9092879672000

x31 = 14.9225651046000

x32 = -98.1747704247000

x33 = -46.3384916404000

x34 = 40.0553063333000

x35 = 65.1880475620000

x36 = 47.9092879672000

x37 = 16.4933614313000

x38 = -40.0553063333000

x39 = -3.92699081699000

x40 = 98.1747704247000

x41 = 41.6261026601000

x42 = 52.6216769476000

x43 = -73.0420291960000

x44 = -79.3252145031000

x45 = 58.9048622548000

x46 = -91.8915851175000

x47 = -58.9048622548000

x48 = -22.7765467385000

x49 = -84.0376034835000

x50 = -27.4889357189000

x51 = -52.6216769476000

x52 = -21.2057504117000

x53 = -8.63937979737000

x54 = -35.3429173529000

x55 = -41.6261026601000

x56 = 84.0376034835000

x57 = 46.3384916404000

x58 = 91.8915851175000

x59 = -14.9225651046000

x60 = -96.6039740979000

x61 = -90.3207887907000

x62 = 54.1924732744000

x63 = 27.4889357189000

x64 = 2.35619449019000

x65 = 8.63937979737000

x66 = -65.1880475620000

x67 = 104.457955732000