cos(x)= 2/pi

解答

cos (x) = \frac{2}{π}

x = 0.88068 \dots + 2 πn, x = 2 π - 0.88068 \dots + 2 πn

度数

x = 50.45977 \dots^{\circ} + 36 0^{\circ} n, x = 309.54022 \dots^{\circ} + 36 0^{\circ} n

求解步骤

cos (x) = \frac{2}{π}

使用反三角函数性质

cos (x) = \frac{2}{π}

cos (x) = \frac{2}{π}

的通解

cos (x) = a \Rightarrow x = arccos (a) + 2 πn, x = 2 π - arccos (a) + 2 πn

x = arccos (\frac{2}{π}) + 2 πn, x = 2 π - arccos (\frac{2}{π}) + 2 πn

x = arccos (\frac{2}{π}) + 2 πn, x = 2 π - arccos (\frac{2}{π}) + 2 πn

以小数形式表示解

x = 0.88068 \dots + 2 πn, x = 2 π - 0.88068 \dots + 2 πn

tan^{2} (x) + 3 tan (x) + 1 = 0

csc (2 x) = 2, 0 \leq x < 2 π

sin (x) + cos (x) = 1.2

30 cos (30 x) + 14 = - 16

so l v e f or x, cot (- x) cos (- x) + sin (- x) = - \frac{1}{f}