What is the general solution for cos(x/2)=-(sqrt(2))/2 ?

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

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cos(x/2)=-(sqrt(2))/2

Solution

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

Solution

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

Degrees

x = 27 0^{\circ} + 72 0^{\circ} n, x = 45 0^{\circ} + 72 0^{\circ} n

Solution steps

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

General solutions for

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

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

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

Solve

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

\frac{x}{2} = \frac{3 π}{4} + 2 πn

Multiply both sides by

2

\frac{x}{2} = \frac{3 π}{4} + 2 πn

Multiply both sides by

2

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

Simplify

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

Simplify

\frac{2 x}{2} : x

\frac{2 x}{2}

Divide the numbers:

\frac{2}{2} = 1

= x

Simplify

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

2 \cdot \frac{3 π}{4} + 2 \cdot 2 πn

2 \cdot \frac{3 π}{4} = \frac{3 π}{2}

2 \cdot \frac{3 π}{4}

Multiply fractions:

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

= \frac{3 π 2}{4}

Multiply the numbers:

3 \cdot 2 = 6

= \frac{6 π}{4}

Cancel the common factor:

2

= \frac{3 π}{2}

2 \cdot 2 πn = 4 πn

2 \cdot 2 πn

Multiply the numbers:

2 \cdot 2 = 4

= 4 πn

= \frac{3 π}{2} + 4 πn

x = \frac{3 π}{2} + 4 πn

x = \frac{3 π}{2} + 4 πn

x = \frac{3 π}{2} + 4 πn

Solve

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

\frac{x}{2} = \frac{5 π}{4} + 2 πn

Multiply both sides by

2

\frac{x}{2} = \frac{5 π}{4} + 2 πn

Multiply both sides by

2

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

Simplify

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

Simplify

\frac{2 x}{2} : x

\frac{2 x}{2}

Divide the numbers:

\frac{2}{2} = 1

= x

Simplify

2 \cdot \frac{5 π}{4} + 2 \cdot 2 πn : \frac{5 π}{2} + 4 πn

2 \cdot \frac{5 π}{4} + 2 \cdot 2 πn

2 \cdot \frac{5 π}{4} = \frac{5 π}{2}

2 \cdot \frac{5 π}{4}

Multiply fractions:

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

= \frac{5 π 2}{4}

Multiply the numbers:

5 \cdot 2 = 10

= \frac{10 π}{4}

Cancel the common factor:

2

= \frac{5 π}{2}

2 \cdot 2 πn = 4 πn

2 \cdot 2 πn

Multiply the numbers:

2 \cdot 2 = 4

= 4 πn

= \frac{5 π}{2} + 4 πn

x = \frac{5 π}{2} + 4 πn

x = \frac{5 π}{2} + 4 πn

x = \frac{5 π}{2} + 4 πn

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

Popular Examples

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0 = 1 - cos (2 x)

sec^2(x)+2=3sec(x)

sec^{2} (x) + 2 = 3 sec (x)

cos(x)-1=-cos(x)

cos (x) - 1 = - cos (x)

2cos^2(x)=3

2 cos^{2} (x) = 3

9tan(2x)-9cot(x)=0

9 tan (2 x) - 9 cot (x) = 0

Frequently Asked Questions (FAQ)

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