cos(t)=-3/5

解答

cos (t) = - \frac{3}{5}

t = 2.21429 \dots + 2 πn, t = - 2.21429 \dots + 2 πn

度数

t = 126.86989 \dots^{\circ} + 36 0^{\circ} n, t = - 126.86989 \dots^{\circ} + 36 0^{\circ} n

求解步骤

cos (t) = - \frac{3}{5}

使用反三角函数性质

cos (t) = - \frac{3}{5}

cos (t) = - \frac{3}{5}

的通解

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

t = arccos (- \frac{3}{5}) + 2 πn, t = - arccos (- \frac{3}{5}) + 2 πn

t = arccos (- \frac{3}{5}) + 2 πn, t = - arccos (- \frac{3}{5}) + 2 πn

以小数形式表示解

t = 2.21429 \dots + 2 πn, t = - 2.21429 \dots + 2 πn