What is the general solution for cos(θ)=-1/4 ?

The general solution for cos(θ)=-1/4 is θ=1.82347…+2pin,θ=-1.82347…+2pin

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cos(θ)=-1/4

cos (θ) = - \frac{1}{4}

θ = 1.82347 \dots + 2 πn, θ = - 1.82347 \dots + 2 πn

Solution steps

cos (θ) = - \frac{1}{4}

Apply trig inverse properties

θ = arccos (- \frac{1}{4}) + 2 πn, θ = - arccos (- \frac{1}{4}) + 2 πn

Show solutions in decimal form

θ = 1.82347 \dots + 2 πn, θ = - 1.82347 \dots + 2 πn

sin (2 x) = 2 cos^{2} (x)

cos (x) = 3

sin (2 θ) = 3 cos (θ)

cos (θ) = - \frac{2}{5}

tan^{2} (θ) - 3 = 0

What is the general solution for cos(θ)=-1/4 ?
The general solution for cos(θ)=-1/4 is θ=1.82347…+2pin,θ=-1.82347…+2pin