What is the general solution for -2sin(x)-2sin(2x)=0 ?

The general solution for -2sin(x)-2sin(2x)=0 is x=2pin,x=pi+2pin,x=(2pi)/3+2pin,x=(4pi)/3+2pin

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Popular >

-2sin(x)-2sin(2x)=0

Solution

- 2 sin (x) - 2 sin (2 x) = 0

Solution

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

Degrees

x = 0^{\circ} + 36 0^{\circ} n, x = 18 0^{\circ} + 36 0^{\circ} n, x = 12 0^{\circ} + 36 0^{\circ} n, x = 24 0^{\circ} + 36 0^{\circ} n

Solution steps

- 2 sin (x) - 2 sin (2 x) = 0

Rewrite using trig identities

- 2 sin (2 x) - 2 sin (x)

Use the Double Angle identity:

sin (2 x) = 2 sin (x) cos (x)

= - 2 \cdot 2 sin (x) cos (x) - 2 sin (x)

Simplify

= - 4 sin (x) cos (x) - 2 sin (x)

- 2 sin (x) - 4 cos (x) sin (x) = 0

Factor

- 2 sin (x) - 4 cos (x) sin (x) : - 2 sin (x) (2 cos (x) + 1)

- 2 sin (x) - 4 cos (x) sin (x)

Rewrite

- 4

2 \cdot 2

= - 2 sin (x) + 2 \cdot 2 sin (x) cos (x)

Factor out common term

- 2 sin (x)

= - 2 sin (x) (1 + 2 cos (x))

- 2 sin (x) (2 cos (x) + 1) = 0

Solving each part separately

sin (x) = 0 or 2 cos (x) + 1 = 0

sin (x) = 0 : x = 2 πn, x = π + 2 πn

sin (x) = 0

General solutions for

sin (x) = 0

sin (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} sin (x) 0 \frac{1}{2} \frac{2}{2} \frac{3}{2} 1 \frac{3}{2} \frac{2}{2} \frac{1}{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} sin (x) 0 - \frac{1}{2} - \frac{2}{2} - \frac{3}{2} - 1 - \frac{3}{2} - \frac{2}{2} - \frac{1}{2}

x = 0 + 2 πn, x = π + 2 πn

x = 0 + 2 πn, x = π + 2 πn

Solve

x = 0 + 2 πn : x = 2 πn

x = 0 + 2 πn

0 + 2 πn = 2 πn

x = 2 πn

x = 2 πn, x = π + 2 πn

2 cos (x) + 1 = 0 : x = \frac{2 π}{3} + 2 πn, x = \frac{4 π}{3} + 2 πn

2 cos (x) + 1 = 0

Move

1

to the right side

2 cos (x) + 1 = 0

Subtract

1

from both sides

2 cos (x) + 1 - 1 = 0 - 1

Simplify

2 cos (x) = - 1

2 cos (x) = - 1

Divide both sides by

2

2 cos (x) = - 1

Divide both sides by

2

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

Simplify

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

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

Combine all the solutions

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

Popular Examples

((sin^2(x)+1))/(1-sin^2(x))-1=2

\frac{( sin ^{2} ( x ) + 1 )}{1 - sin ^{2} ( x )} - 1 = 2

tan(2θ)+sqrt(3)=0

tan (2 θ) + 3 = 0

-2sin(θ)+cos(2θ)=1

- 2 sin (θ) + cos (2 θ) = 1

cos(2x+60)=sin(3x)

cos (2 x + 60) = sin (3 x)

csc(θ)=-3/2

csc (θ) = - \frac{3}{2}

Frequently Asked Questions (FAQ)

What is the general solution for -2sin(x)-2sin(2x)=0 ?
The general solution for -2sin(x)-2sin(2x)=0 is x=2pin,x=pi+2pin,x=(2pi)/3+2pin,x=(4pi)/3+2pin