(1/2)=cos(4*x)

Разделим обе части ур-ния на -1

Ур-ние превратится в
$$cos{left (4 x right )} = frac{1}{2}$$
Это ур-ние преобразуется в
$$4 x = pi n + {acos}{left (frac{1}{2} right )}$$
$$4 x = pi n – pi + {acos}{left (frac{1}{2} right )}$$
Или
$$4 x = pi n + frac{pi}{3}$$
$$4 x = pi n – frac{2 pi}{3}$$
, где n – любое целое число
Разделим обе части полученного ур-ния на
$$4$$
получим ответ:
$$x_{1} = frac{pi n}{4} + frac{pi}{12}$$
$$x_{2} = frac{pi n}{4} – frac{pi}{6}$$

pi
x1 = —
12

5*pi
x2 = —-
12

x1 = 8.11578102177000

x2 = 23.8237442897000

x3 = -64.6644487864000

x4 = 15.9697626557000

x5 = -45.8148928649000

x6 = -65.7116463376000

x7 = 85.0848010347000

x8 = -13.8753675534000

x9 = -30.1069295969000

x10 = 56.2868683768000

x11 = -67.8060414400000

x12 = 74.0892267472000

x13 = 30.1069295969000

x14 = -50.0036830696000

x15 = 67.8060414400000

x16 = 1448.53601269000

x17 = 20.1585528605000

x18 = -28.0125344945000

x19 = 48.4328867428000

x20 = 93.9859802199000

x21 = 86.1319985859000

x22 = -6.02138591938000

x23 = -45.2912940893000

x24 = -100.269165527000

x25 = 70.4240353180000

x26 = -42.1497014357000

x27 = -39.5317075577000

x28 = 64.1408500108000

x29 = 12.3045712266000

x30 = 87.7027949127000

x31 = -81.9432083811000

x32 = -1.83259571459000

x33 = -31.6777259237000

x34 = 0.261799387799000

x35 = -23.8237442897000

x36 = -20.1585528605000

x37 = 71.9948316448000

x38 = 42.1497014357000

x39 = -52.0980781720000

x40 = -17.5405589825000

x41 = -97.6511716491000

x42 = 92.4151838931000

x43 = -61.5228561328000

x44 = -96.0803753223000

x45 = -9.68657734857000

x46 = -35.8665161285000

x47 = -86.1319985859000

x48 = 45.8148928649000

x49 = -93.9859802199000

x50 = 4.45058959259000

x51 = 66.2352451132000

x52 = -43.7204977625000

x53 = -37.9609112309000

x54 = 59.9520598060000

x55 = 52.0980781720000

x56 = 34.2957198017000

x57 = 62.5700536840000

x58 = 26.4417381677000

x59 = 1.83259571459000

x60 = 92.9387826687000

x61 = 96.0803753223000

x62 = -57.8576647036000

x63 = 126.972703083000

x64 = 22.2529479629000

x65 = -15.9697626557000

x66 = -87.7027949127000

x67 = -89.7971900151000

x68 = -71.9948316448000

x69 = 100.269165527000

x70 = -12.8281700022000

x71 = -64.1408500108000

x72 = -59.9520598060000

x73 = -83.5140047079000

x74 = 9.16297857297000

x75 = -75.6600230740000

x76 = -53.6688744988000

x77 = 468.359104773000

x78 = 78.2780169519000

x79 = 89.7971900151000

x80 = 50.0036830696000

x81 = 28.0125344945000

x82 = 37.9609112309000

x83 = 6.02138591938000

x84 = -21.7293491873000

x85 = -78.2780169519000

x86 = 81.9432083811000

x87 = 88.2263936883000

x88 = -34.8193185773000

x89 = -74.0892267472000

x90 = 44.2440965381000

x91 = -79.8488132787000