arccos(x)=180

解答

arccos (x) = 18 0^{\circ}

x = - 1

求解步骤

arccos (x) = 18 0^{\circ}

使用反三角函数性质

arccos (x) = 18 0^{\circ}

arccos (x) = a \Rightarrow x = cos (a)

x = cos (18 0^{\circ})

cos (18 0^{\circ}) = - 1

cos (18 0^{\circ})

使用以下普通恒等式:

cos (18 0^{\circ}) = (- 1)

cos (18 0^{\circ})

cos (x)

周期表（周期为

36 0^{\circ} n

）：

x 0 3 0^{\circ} 4 5^{\circ} 6 0^{\circ} 9 0^{\circ} 12 0^{\circ} 13 5^{\circ} 15 0^{\circ} cos (x) 1 \frac{3}{2} \frac{2}{2} \frac{1}{2} 0 - \frac{1}{2} - \frac{2}{2} - \frac{3}{2} x 18 0^{\circ} 21 0^{\circ} 22 5^{\circ} 24 0^{\circ} 27 0^{\circ} 30 0^{\circ} 31 5^{\circ} 33 0^{\circ} cos (x) - 1 - \frac{3}{2} - \frac{2}{2} - \frac{1}{2} 0 \frac{1}{2} \frac{2}{2} \frac{3}{2}

= (- 1)

= - 1

x = - 1

x = - 1

sin (a) = \frac{29.7}{54.5}

1.0003 sin (3 0^{\circ}) = 1.46 sin (x)

cos (x) = - \frac{5}{34}

cos (x) = cos (x - c)

- 22 cos (θ) = 2