What is the general solution for sqrt(2)cos(3θ)+1=0 ?

The general solution for sqrt(2)cos(3θ)+1=0 is θ= pi/4+(2pin)/3 ,θ=(5pi}{12}+\frac{2pin)/3

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sqrt(2)cos(3θ)+1=0

Solution

2 cos (3 θ) + 1 = 0

Solution

θ = \frac{π}{4} + \frac{2 πn}{3}, θ = \frac{5 π}{12} + \frac{2 πn}{3}

Degrees

θ = 4 5^{\circ} + 12 0^{\circ} n, θ = 7 5^{\circ} + 12 0^{\circ} n

Solution steps

2 cos (3 θ) + 1 = 0

Move

1

to the right side

2 cos (3 θ) + 1 = 0

Subtract

1

from both sides

2 cos (3 θ) + 1 - 1 = 0 - 1

Simplify

2 cos (3 θ) = - 1

2 cos (3 θ) = - 1

Divide both sides by

2

2 cos (3 θ) = - 1

Divide both sides by

2

\frac{2 cos ( 3 θ )}{2} = \frac{- 1}{2}

Simplify

\frac{2 cos ( 3 θ )}{2} = \frac{- 1}{2}

Simplify

\frac{2 cos ( 3 θ )}{2} : cos (3 θ)

\frac{2 cos ( 3 θ )}{2}

Cancel the common factor:

2

= cos (3 θ)

Simplify

\frac{- 1}{2} : - \frac{2}{2}

\frac{- 1}{2}

Apply the fraction rule:

\frac{- a}{b} = - \frac{a}{b}

= - \frac{1}{2}

Rationalize

- \frac{1}{2} : - \frac{2}{2}

- \frac{1}{2}

Multiply by the conjugate

\frac{2}{2}

= - \frac{1 \cdot 2}{2 2}

1 \cdot 2 = 2

22 = 2

22

Apply radical rule:

a a = a

22 = 2

= 2

= - \frac{2}{2}

= - \frac{2}{2}

cos (3 θ) = - \frac{2}{2}

cos (3 θ) = - \frac{2}{2}

cos (3 θ) = - \frac{2}{2}

General solutions for

cos (3 θ) = - \frac{2}{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}

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

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

Solve

3 θ = \frac{3 π}{4} + 2 πn : θ = \frac{π}{4} + \frac{2 πn}{3}

3 θ = \frac{3 π}{4} + 2 πn

Divide both sides by

3

3 θ = \frac{3 π}{4} + 2 πn

Divide both sides by

3

\frac{3 θ}{3} = \frac{\frac{3 π}{4}}{3} + \frac{2 πn}{3}

Simplify

\frac{3 θ}{3} = \frac{\frac{3 π}{4}}{3} + \frac{2 πn}{3}

Simplify

\frac{3 θ}{3} : θ

\frac{3 θ}{3}

Divide the numbers:

\frac{3}{3} = 1

= θ

Simplify

\frac{\frac{3 π}{4}}{3} + \frac{2 πn}{3} : \frac{π}{4} + \frac{2 πn}{3}

\frac{\frac{3 π}{4}}{3} + \frac{2 πn}{3}

\frac{\frac{3 π}{4}}{3} = \frac{π}{4}

\frac{\frac{3 π}{4}}{3}

Apply the fraction rule:

\frac{\frac{b}{c}}{a} = \frac{b}{c \cdot a}

= \frac{3 π}{4 \cdot 3}

Multiply the numbers:

4 \cdot 3 = 12

= \frac{3 π}{12}

Cancel the common factor:

3

= \frac{π}{4}

= \frac{π}{4} + \frac{2 πn}{3}

θ = \frac{π}{4} + \frac{2 πn}{3}

θ = \frac{π}{4} + \frac{2 πn}{3}

θ = \frac{π}{4} + \frac{2 πn}{3}

Solve

3 θ = \frac{5 π}{4} + 2 πn : θ = \frac{5 π}{12} + \frac{2 πn}{3}

3 θ = \frac{5 π}{4} + 2 πn

Divide both sides by

3

3 θ = \frac{5 π}{4} + 2 πn

Divide both sides by

3

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

Simplify

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

Simplify

\frac{3 θ}{3} : θ

\frac{3 θ}{3}

Divide the numbers:

\frac{3}{3} = 1

= θ

Simplify

\frac{\frac{5 π}{4}}{3} + \frac{2 πn}{3} : \frac{5 π}{12} + \frac{2 πn}{3}

\frac{\frac{5 π}{4}}{3} + \frac{2 πn}{3}

\frac{\frac{5 π}{4}}{3} = \frac{5 π}{12}

\frac{\frac{5 π}{4}}{3}

Apply the fraction rule:

\frac{\frac{b}{c}}{a} = \frac{b}{c \cdot a}

= \frac{5 π}{4 \cdot 3}

Multiply the numbers:

4 \cdot 3 = 12

= \frac{5 π}{12}

= \frac{5 π}{12} + \frac{2 πn}{3}

θ = \frac{5 π}{12} + \frac{2 πn}{3}

θ = \frac{5 π}{12} + \frac{2 πn}{3}

θ = \frac{5 π}{12} + \frac{2 πn}{3}

θ = \frac{π}{4} + \frac{2 πn}{3}, θ = \frac{5 π}{12} + \frac{2 πn}{3}

Popular Examples

cos(a)=-3/5

cos (a) = - \frac{3}{5}

tan(x)=3.5

tan (x) = 3.5

sec(θ)= 1/(sec(θ))

sec (θ) = \frac{1}{sec ( θ )}

-2tan(θ)+1=3tan(θ)-7

- 2 tan (θ) + 1 = 3 tan (θ) - 7

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

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

Frequently Asked Questions (FAQ)

What is the general solution for sqrt(2)cos(3θ)+1=0 ?
The general solution for sqrt(2)cos(3θ)+1=0 is θ= pi/4+(2pin)/3 ,θ=(5pi}{12}+\frac{2pin)/3