What is the general solution for cos(x)= 4/5 ?

The general solution for cos(x)= 4/5 is x=0.64350…+2pin,x=2pi-0.64350…+2pin

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cos(x)= 4/5

cos (x) = \frac{4}{5}

x = 0.64350 \dots + 2 πn, x = 2 π - 0.64350 \dots + 2 πn

Solution steps

cos (x) = \frac{4}{5}

Apply trig inverse properties

x = arccos (\frac{4}{5}) + 2 πn, x = 2 π - arccos (\frac{4}{5}) + 2 πn

Show solutions in decimal form

x = 0.64350 \dots + 2 πn, x = 2 π - 0.64350 \dots + 2 πn

tan (x) - 1 = 0

tan^{2} (θ) - 3 tan (θ) + 2 = 0

tan (θ) = \frac{1}{3}

2 cos^{2} (x) - cos (x) = 0

4 sin (x) cos (x) = 1

What is the general solution for cos(x)= 4/5 ?
The general solution for cos(x)= 4/5 is x=0.64350…+2pin,x=2pi-0.64350…+2pin