What is the general solution for cos(x)= 15/21 ?

The general solution for cos(x)= 15/21 is x=0.77519…+2pin,x=2pi-0.77519…+2pin

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cos(x)= 15/21

cos (x) = \frac{15}{21}

x = 0.77519 \dots + 2 πn, x = 2 π - 0.77519 \dots + 2 πn

Degrees

x = 44.41530 \dots^{\circ} + 36 0^{\circ} n, x = 315.58469 \dots^{\circ} + 36 0^{\circ} n

Solution steps

cos (x) = \frac{15}{21}

Cancel the common factor:

3

cos (x) = \frac{5}{7}

Apply trig inverse properties

cos (x) = \frac{5}{7}

General solutions for

cos (x) = \frac{5}{7}

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

x = arccos (\frac{5}{7}) + 2 πn, x = 2 π - arccos (\frac{5}{7}) + 2 πn

x = arccos (\frac{5}{7}) + 2 πn, x = 2 π - arccos (\frac{5}{7}) + 2 πn

Show solutions in decimal form

x = 0.77519 \dots + 2 πn, x = 2 π - 0.77519 \dots + 2 πn

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

2 cos (x) - 1 = 0, 0 \leq x < 2 π

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

cos (4 θ) = - \frac{2}{3}

3 + 4 cos (2 x) + 2 cos (4 x) = 0

What is the general solution for cos(x)= 15/21 ?
The general solution for cos(x)= 15/21 is x=0.77519…+2pin,x=2pi-0.77519…+2pin