What is the general solution for cos(2x)= 7/9 ?

The general solution for cos(2x)= 7/9 is x=(0.67967…)/2+pin,x=pi-(0.67967…)/2+pin

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cos(2x)= 7/9

cos (2 x) = \frac{7}{9}

x = \frac{0.67967 \dots}{2} + πn, x = π - \frac{0.67967 \dots}{2} + πn

Solution steps

cos (2 x) = \frac{7}{9}

Apply trig inverse properties

2 x = arccos (\frac{7}{9}) + 2 πn, 2 x = 2 π - arccos (\frac{7}{9}) + 2 πn

Solve

2 x = arccos (\frac{7}{9}) + 2 πn : x = \frac{arccos ( \frac{7}{9} )}{2} + πn

Solve

2 x = 2 π - arccos (\frac{7}{9}) + 2 πn : x = π - \frac{arccos ( \frac{7}{9} )}{2} + πn

x = \frac{arccos ( \frac{7}{9} )}{2} + πn, x = π - \frac{arccos ( \frac{7}{9} )}{2} + πn

Show solutions in decimal form

x = \frac{0.67967 \dots}{2} + πn, x = π - \frac{0.67967 \dots}{2} + πn

- 2 tan (θ) = - tan^{2} (θ) - 1

sin^{2} (x) + 6 sin (x) = 5

x, y + y = tan (x)

cos (2 x) = \frac{1}{13}

cos (θ) = 0, D = R (θ)

What is the general solution for cos(2x)= 7/9 ?
The general solution for cos(2x)= 7/9 is x=(0.67967…)/2+pin,x=pi-(0.67967…)/2+pin