What is the general solution for |cos(x)|= 1/2 ?

The general solution for |cos(x)|= 1/2 is x=(2pi)/3+2pin,x=(4pi)/3+2pin,x= pi/3+2pin,x=(5pi)/3+2pin

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|cos(x)|= 1/2

∣ cos (x) ∣ = \frac{1}{2}

x = \frac{2 π}{3} + 2 πn, x = \frac{4 π}{3} + 2 πn, x = \frac{π}{3} + 2 πn, x = \frac{5 π}{3} + 2 πn

Degrees

x = 12 0^{\circ} + 36 0^{\circ} n, x = 24 0^{\circ} + 36 0^{\circ} n, x = 6 0^{\circ} + 36 0^{\circ} n, x = 30 0^{\circ} + 36 0^{\circ} n

Solution steps

∣ cos (x) ∣ = \frac{1}{2}

Solve by substitution

∣ cos (x) ∣ = \frac{1}{2}

Let:

cos (x) = u

∣ u ∣ = \frac{1}{2}

∣ u ∣ = \frac{1}{2} : u = - \frac{1}{2} or u = \frac{1}{2}

∣ u ∣ = \frac{1}{2}

Apply absolute rule: If

∣ u ∣ = a, a > 0

then

u = a

u = - a

u = - \frac{1}{2} or u = \frac{1}{2}

Substitute back

u = cos (x)

cos (x) = - \frac{1}{2} or cos (x) = \frac{1}{2}

cos (x) = - \frac{1}{2} or cos (x) = \frac{1}{2}

cos (x) = - \frac{1}{2} : x = \frac{2 π}{3} + 2 πn, x = \frac{4 π}{3} + 2 πn

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

General solutions for

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

cos (x)

periodicity table with

2 πn

cycle:

x 0 \frac{π}{6} \frac{π}{4} \frac{π}{3} \frac{π}{2} \frac{2 π}{3} \frac{3 π}{4} \frac{5 π}{6} cos (x) 1 \frac{3}{2} \frac{2}{2} \frac{1}{2} 0 - \frac{1}{2} - \frac{2}{2} - \frac{3}{2} x π \frac{7 π}{6} \frac{5 π}{4} \frac{4 π}{3} \frac{3 π}{2} \frac{5 π}{3} \frac{7 π}{4} \frac{11 π}{6} cos (x) - 1 - \frac{3}{2} - \frac{2}{2} - \frac{1}{2} 0 \frac{1}{2} \frac{2}{2} \frac{3}{2}

x = \frac{2 π}{3} + 2 πn, x = \frac{4 π}{3} + 2 πn

x = \frac{2 π}{3} + 2 πn, x = \frac{4 π}{3} + 2 πn

cos (x) = \frac{1}{2} : x = \frac{π}{3} + 2 πn, x = \frac{5 π}{3} + 2 πn

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

General solutions for

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

cos (x)

periodicity table with

2 πn

cycle:

x 0 \frac{π}{6} \frac{π}{4} \frac{π}{3} \frac{π}{2} \frac{2 π}{3} \frac{3 π}{4} \frac{5 π}{6} cos (x) 1 \frac{3}{2} \frac{2}{2} \frac{1}{2} 0 - \frac{1}{2} - \frac{2}{2} - \frac{3}{2} x π \frac{7 π}{6} \frac{5 π}{4} \frac{4 π}{3} \frac{3 π}{2} \frac{5 π}{3} \frac{7 π}{4} \frac{11 π}{6} cos (x) - 1 - \frac{3}{2} - \frac{2}{2} - \frac{1}{2} 0 \frac{1}{2} \frac{2}{2} \frac{3}{2}

x = \frac{π}{3} + 2 πn, x = \frac{5 π}{3} + 2 πn

x = \frac{π}{3} + 2 πn, x = \frac{5 π}{3} + 2 πn

Combine all the solutions

x = \frac{2 π}{3} + 2 πn, x = \frac{4 π}{3} + 2 πn, x = \frac{π}{3} + 2 πn, x = \frac{5 π}{3} + 2 πn

sin^{2} (θ) - cos^{2} (θ) = 0

sec (x) = tan (x) + 1

5 cos (2 x) + 1 = 3 cos (2 x)

2 sin (4 x) + 6 = 5

7 sin (x) tan (x) = - 8 tan (x)

What is the general solution for |cos(x)|= 1/2 ?
The general solution for |cos(x)|= 1/2 is x=(2pi)/3+2pin,x=(4pi)/3+2pin,x= pi/3+2pin,x=(5pi)/3+2pin