What is the general solution for csc(x)+cot(x)=(sqrt(3))/3 ?

The general solution for csc(x)+cot(x)=(sqrt(3))/3 is x=(2pi)/3+2pin

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Popular Trigonometry >

csc(x)+cot(x)=(sqrt(3))/3

Solution

csc (x) + cot (x) = \frac{3}{3}

Solution

x = \frac{2 π}{3} + 2 πn

Degrees

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

Solution steps

csc (x) + cot (x) = \frac{3}{3}

Subtract

\frac{3}{3}

from both sides

csc (x) + cot (x) - \frac{1}{3} = 0

Simplify

csc (x) + cot (x) - \frac{1}{3} : \frac{3 csc ( x ) + 3 cot ( x ) - 1}{3}

csc (x) + cot (x) - \frac{1}{3}

Convert element to fraction:

csc (x) = \frac{csc ( x ) 3}{3}, cot (x) = \frac{cot ( x ) 3}{3}

= \frac{csc ( x ) 3}{3} + \frac{cot ( x ) 3}{3} - \frac{1}{3}

Since the denominators are equal, combine the fractions:

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

= \frac{csc ( x ) 3 + cot ( x ) 3 - 1}{3}

\frac{3 csc ( x ) + 3 cot ( x ) - 1}{3} = 0

\frac{f ( x )}{g ( x )} = 0 \Rightarrow f (x) = 0

3 csc (x) + 3 cot (x) - 1 = 0

Express with sin, cos

3 \frac{1}{sin ( x )} + 3 \frac{cos ( x )}{sin ( x )} - 1 = 0

Simplify

3 \frac{1}{sin ( x )} + 3 \frac{cos ( x )}{sin ( x )} - 1 : \frac{3 + 3 cos ( x ) - sin ( x )}{sin ( x )}

3 \frac{1}{sin ( x )} + 3 \frac{cos ( x )}{sin ( x )} - 1

3 \frac{1}{sin ( x )} = \frac{3}{sin ( x )}

3 \frac{1}{sin ( x )}

Multiply fractions:

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

= \frac{1 \cdot 3}{sin ( x )}

Multiply:

1 \cdot 3 = 3

= \frac{3}{sin ( x )}

3 \frac{cos ( x )}{sin ( x )} = \frac{3 cos ( x )}{sin ( x )}

3 \frac{cos ( x )}{sin ( x )}

Multiply fractions:

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

= \frac{cos ( x ) 3}{sin ( x )}

= \frac{3}{sin ( x )} + \frac{3 cos ( x )}{sin ( x )} - 1

Combine the fractions

\frac{3}{sin ( x )} + \frac{3 cos ( x )}{sin ( x )} : \frac{3 + 3 cos ( x )}{sin ( x )}

Apply rule

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

= \frac{3 + 3 cos ( x )}{sin ( x )}

= \frac{3 cos ( x ) + 3}{sin ( x )} - 1

Convert element to fraction:

1 = \frac{1 sin ( x )}{sin ( x )}

= \frac{3 + cos ( x ) 3}{sin ( x )} - \frac{1 \cdot sin ( x )}{sin ( x )}

Since the denominators are equal, combine the fractions:

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

= \frac{3 + cos ( x ) 3 - 1 \cdot sin ( x )}{sin ( x )}

Multiply:

1 \cdot sin (x) = sin (x)

= \frac{3 + 3 cos ( x ) - sin ( x )}{sin ( x )}

\frac{3 + 3 cos ( x ) - sin ( x )}{sin ( x )} = 0

\frac{f ( x )}{g ( x )} = 0 \Rightarrow f (x) = 0

3 + 3 cos (x) - sin (x) = 0

Add

sin (x)

to both sides

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

Square both sides

(3 + 3 cos (x))^{2} = sin^{2} (x)

Subtract

sin^{2} (x)

from both sides

(3 + 3 cos (x))^{2} - sin^{2} (x) = 0

Rewrite using trig identities

(3 + cos (x) 3)^{2} - sin^{2} (x)

Use the Pythagorean identity:

cos^{2} (x) + sin^{2} (x) = 1

sin^{2} (x) = 1 - cos^{2} (x)

= (3 + cos (x) 3)^{2} - (1 - cos^{2} (x))

Simplify

(3 + cos (x) 3)^{2} - (1 - cos^{2} (x)) : 4 cos^{2} (x) + 6 cos (x) + 2

(3 + cos (x) 3)^{2} - (1 - cos^{2} (x))

= (3 + 3 cos (x))^{2} - (1 - cos^{2} (x))

(3 + cos (x) 3)^{2} : 3 + 6 cos (x) + 3 cos^{2} (x)

Apply Perfect Square Formula:

(a + b)^{2} = a^{2} + 2 ab + b^{2}

a = 3, b = cos (x) 3

= (3)^{2} + 23 cos (x) 3 + (cos (x) 3)^{2}

Simplify

(3)^{2} + 23 cos (x) 3 + (cos (x) 3)^{2} : 3 + 6 cos (x) + 3 cos^{2} (x)

(3)^{2} + 23 cos (x) 3 + (cos (x) 3)^{2}

(3)^{2} = 3

(3)^{2}

Apply radical rule:

a = a^{\frac{1}{2}}

= (3^{\frac{1}{2}})^{2}

Apply exponent rule:

(a^{b})^{c} = a^{b c}

= 3^{\frac{1}{2} \cdot 2}

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

\frac{1}{2} \cdot 2

Multiply fractions:

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

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

Cancel the common factor:

2

= 1

= 3

23 cos (x) 3 = 6 cos (x)

23 cos (x) 3

Apply radical rule:

a a = a

33 = 3

= 2 \cdot 3 cos (x)

Multiply the numbers:

2 \cdot 3 = 6

= 6 cos (x)

(cos (x) 3)^{2} = 3 cos^{2} (x)

(cos (x) 3)^{2}

Apply exponent rule:

(a \cdot b)^{n} = a^{n} b^{n}

= (3)^{2} cos^{2} (x)

(3)^{2} : 3

Apply radical rule:

a = a^{\frac{1}{2}}

= (3^{\frac{1}{2}})^{2}

Apply exponent rule:

(a^{b})^{c} = a^{b c}

= 3^{\frac{1}{2} \cdot 2}

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

\frac{1}{2} \cdot 2

Multiply fractions:

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

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

Cancel the common factor:

2

= 1

= 3

= cos^{2} (x) \cdot 3

= 3 + 6 cos (x) + 3 cos^{2} (x)

= 3 + 6 cos (x) + 3 cos^{2} (x)

= 3 + 6 cos (x) + 3 cos^{2} (x) - (1 - cos^{2} (x))

- (1 - cos^{2} (x)) : - 1 + cos^{2} (x)

- (1 - cos^{2} (x))

Distribute parentheses

= - (1) - (- cos^{2} (x))

Apply minus-plus rules

- (- a) = a, - (a) = - a

= - 1 + cos^{2} (x)

= 3 + 6 cos (x) + 3 cos^{2} (x) - 1 + cos^{2} (x)

Simplify

3 + 6 cos (x) + 3 cos^{2} (x) - 1 + cos^{2} (x) : 4 cos^{2} (x) + 6 cos (x) + 2

3 + 6 cos (x) + 3 cos^{2} (x) - 1 + cos^{2} (x)

Group like terms

= 6 cos (x) + 3 cos^{2} (x) + cos^{2} (x) + 3 - 1

Add similar elements:

3 cos^{2} (x) + cos^{2} (x) = 4 cos^{2} (x)

= 6 cos (x) + 4 cos^{2} (x) + 3 - 1

Add/Subtract the numbers:

3 - 1 = 2

= 4 cos^{2} (x) + 6 cos (x) + 2

= 4 cos^{2} (x) + 6 cos (x) + 2

= 4 cos^{2} (x) + 6 cos (x) + 2

2 + 4 cos^{2} (x) + 6 cos (x) = 0

Solve by substitution

2 + 4 cos^{2} (x) + 6 cos (x) = 0

Let:

cos (x) = u

2 + 4 u^{2} + 6 u = 0

2 + 4 u^{2} + 6 u = 0 : u = - \frac{1}{2}, u = - 1

2 + 4 u^{2} + 6 u = 0

Write in the standard form

a x^{2} + b x + c = 0

4 u^{2} + 6 u + 2 = 0

Solve with the quadratic formula

4 u^{2} + 6 u + 2 = 0

Quadratic Equation Formula:

For

a = 4, b = 6, c = 2

u_{1, 2} = \frac{- 6 \pm 6 ^{2} - 4 \cdot 4 \cdot 2}{2 \cdot 4}

u_{1, 2} = \frac{- 6 \pm 6 ^{2} - 4 \cdot 4 \cdot 2}{2 \cdot 4}

6^{2} - 4 \cdot 4 \cdot 2 = 2

6^{2} - 4 \cdot 4 \cdot 2

Multiply the numbers:

4 \cdot 4 \cdot 2 = 32

= 6^{2} - 32

6^{2} = 36

= 36 - 32

Subtract the numbers:

36 - 32 = 4

= 4

Factor the number:

4 = 2^{2}

= 2^{2}

Apply radical rule:

2^{2} = 2

= 2

u_{1, 2} = \frac{- 6 \pm 2}{2 \cdot 4}

Separate the solutions

u_{1} = \frac{- 6 + 2}{2 \cdot 4}, u_{2} = \frac{- 6 - 2}{2 \cdot 4}

u = \frac{- 6 + 2}{2 \cdot 4} : - \frac{1}{2}

\frac{- 6 + 2}{2 \cdot 4}

Add/Subtract the numbers:

- 6 + 2 = - 4

= \frac{- 4}{2 \cdot 4}

Multiply the numbers:

2 \cdot 4 = 8

= \frac{- 4}{8}

Apply the fraction rule:

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

= - \frac{4}{8}

Cancel the common factor:

4

= - \frac{1}{2}

u = \frac{- 6 - 2}{2 \cdot 4} : - 1

\frac{- 6 - 2}{2 \cdot 4}

Subtract the numbers:

- 6 - 2 = - 8

= \frac{- 8}{2 \cdot 4}

Multiply the numbers:

2 \cdot 4 = 8

= \frac{- 8}{8}

Apply the fraction rule:

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

= - \frac{8}{8}

Apply rule

\frac{a}{a} = 1

= - 1

The solutions to the quadratic equation are:

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

Substitute back

u = cos (x)

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

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

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) = - 1 : x = π + 2 πn

cos (x) = - 1

General solutions for

cos (x) = - 1

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 = π + 2 πn

x = π + 2 πn

Combine all the solutions

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

Verify solutions by plugging them into the original equation

Check the solutions by plugging them into

csc (x) + cot (x) = \frac{3}{3}

Remove the ones that don't agree with the equation.

Check the solution

\frac{2 π}{3} + 2 πn :

True

\frac{2 π}{3} + 2 πn

Plug in

n = 1

\frac{2 π}{3} + 2 π 1

For

csc (x) + cot (x) = \frac{3}{3}

plug in

x = \frac{2 π}{3} + 2 π 1

csc (\frac{2 π}{3} + 2 π 1) + cot (\frac{2 π}{3} + 2 π 1) = \frac{3}{3}

Refine

0.57735 \dots = 0.57735 \dots

\Rightarrow True

Check the solution

\frac{4 π}{3} + 2 πn :

False

\frac{4 π}{3} + 2 πn

Plug in

n = 1

\frac{4 π}{3} + 2 π 1

For

csc (x) + cot (x) = \frac{3}{3}

plug in

x = \frac{4 π}{3} + 2 π 1

csc (\frac{4 π}{3} + 2 π 1) + cot (\frac{4 π}{3} + 2 π 1) = \frac{3}{3}

Refine

- 0.57735 \dots = 0.57735 \dots

\Rightarrow False

Check the solution

π + 2 πn :

False

π + 2 πn

Plug in

n = 1

π + 2 π 1

For

csc (x) + cot (x) = \frac{3}{3}

plug in

x = π + 2 π 1

csc (π + 2 π 1) + cot (π + 2 π 1) = \frac{3}{3}

Undefined

\Rightarrow False

x = \frac{2 π}{3} + 2 πn

Graph

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tan^2(x)= 3/2 sec(x)

cot(θ)=cot^2(θ)

Frequently Asked Questions (FAQ)

What is the general solution for csc(x)+cot(x)=(sqrt(3))/3 ?
The general solution for csc(x)+cot(x)=(sqrt(3))/3 is x=(2pi)/3+2pin