cos(θ)=(sqrt(7))/4

解答

cos (θ) = \frac{7}{4}

θ = 0.84806 \dots + 2 πn, θ = 2 π - 0.84806 \dots + 2 πn

度数

θ = 48.59037 \dots^{\circ} + 36 0^{\circ} n, θ = 311.40962 \dots^{\circ} + 36 0^{\circ} n

求解步骤

cos (θ) = \frac{7}{4}

使用反三角函数性质

cos (θ) = \frac{7}{4}

cos (θ) = \frac{7}{4}

的通解

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

θ = arccos (\frac{7}{4}) + 2 πn, θ = 2 π - arccos (\frac{7}{4}) + 2 πn

θ = arccos (\frac{7}{4}) + 2 πn, θ = 2 π - arccos (\frac{7}{4}) + 2 πn

以小数形式表示解

θ = 0.84806 \dots + 2 πn, θ = 2 π - 0.84806 \dots + 2 πn

sin (2 θ - \frac{π}{2}) = - 1, 0 \leq θ \leq 2 π

sin (\frac{π}{11}) = sin (\frac{x π}{11})

3 + cos (4 θ) = 2 - cos (4 θ)

5 sec (θ) = 4 sec (θ) + 2

4 sec (π x) + 6 = - 2