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Popular >

(cos(θ)+sin(θ))^2= 3/2

Solution

(cos (θ) + sin (θ))^{2} = \frac{3}{2}

Solution

θ = 2 πn + \frac{13 π}{12}, θ = 2 πn + \frac{17 π}{12}, θ = 2 πn + \frac{π}{12}, θ = 2 πn + \frac{5 π}{12}

Degrees

θ = 19 5^{\circ} + 36 0^{\circ} n, θ = 25 5^{\circ} + 36 0^{\circ} n, θ = 1 5^{\circ} + 36 0^{\circ} n, θ = 7 5^{\circ} + 36 0^{\circ} n

Solution steps

(cos (θ) + sin (θ))^{2} = \frac{3}{2}

Subtract

\frac{3}{2}

from both sides

(cos (θ) + sin (θ))^{2} - \frac{3}{2} = 0

Simplify

(cos (θ) + sin (θ))^{2} - \frac{3}{2} : \frac{2 ( cos ( θ ) + sin ( θ ) ) ^{2} - 3}{2}

(cos (θ) + sin (θ))^{2} - \frac{3}{2}

Convert element to fraction:

(cos (θ) + sin (θ))^{2} = \frac{( cos ( θ ) + sin ( θ ) ) ^{2} 2}{2}

= \frac{( cos ( θ ) + sin ( θ ) ) ^{2} \cdot 2}{2} - \frac{3}{2}

Since the denominators are equal, combine the fractions:

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

= \frac{( cos ( θ ) + sin ( θ ) ) ^{2} \cdot 2 - 3}{2}

\frac{2 ( cos ( θ ) + sin ( θ ) ) ^{2} - 3}{2} = 0

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

2 (cos (θ) + sin (θ))^{2} - 3 = 0

Factor

2 (cos (θ) + sin (θ))^{2} - 3 : (2 (cos (θ) + sin (θ)) + 3) (2 (cos (θ) + sin (θ)) - 3)

2 (cos (θ) + sin (θ))^{2} - 3

Rewrite

2 (cos (θ) + sin (θ))^{2} - 3

(2 (cos (θ) + sin (θ)))^{2} - (3)^{2}

2 (cos (θ) + sin (θ))^{2} - 3

Apply radical rule:

a = (a)^{2}

2 = (2)^{2}

= (2)^{2} (cos (θ) + sin (θ))^{2} - 3

Apply radical rule:

a = (a)^{2}

3 = (3)^{2}

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

Apply exponent rule:

a^{m} b^{m} = (ab)^{m}

(2)^{2} (cos (θ) + sin (θ))^{2} = (2 (cos (θ) + sin (θ)))^{2}

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

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

Apply Difference of Two Squares Formula:

x^{2} - y^{2} = (x + y) (x - y)

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

= (2 (cos (θ) + sin (θ)) + 3) (2 (cos (θ) + sin (θ)) - 3)

(2 (cos (θ) + sin (θ)) + 3) (2 (cos (θ) + sin (θ)) - 3) = 0

Solving each part separately

2 (cos (θ) + sin (θ)) + 3 = 0 or 2 (cos (θ) + sin (θ)) - 3 = 0

2 (cos (θ) + sin (θ)) + 3 = 0 : θ = 2 πn + \frac{13 π}{12}, θ = 2 πn + \frac{17 π}{12}

2 (cos (θ) + sin (θ)) + 3 = 0

Rewrite using trig identities

2 (cos (θ) + sin (θ)) + 3

sin (θ) + cos (θ) = 2 sin (θ + \frac{π}{4})

sin (θ) + cos (θ)

Rewrite as

= 2 (\frac{1}{2} sin (θ) + \frac{1}{2} cos (θ))

Use the following trivial identity:

cos (\frac{π}{4}) = \frac{1}{2}

Use the following trivial identity:

sin (\frac{π}{4}) = \frac{1}{2}

= 2 (cos (\frac{π}{4}) sin (θ) + sin (\frac{π}{4}) cos (θ))

Use the Angle Sum identity:

sin (s + t) = sin (s) cos (t) + cos (s) sin (t)

= 2 sin (θ + \frac{π}{4})

= 3 + 22 sin (θ + \frac{π}{4})

3 + 22 sin (θ + \frac{π}{4}) = 0

Apply radical rule:

a a = a

22 = 2

3 + 2 sin (θ + \frac{π}{4}) = 0

Move

3

to the right side

3 + 2 sin (θ + \frac{π}{4}) = 0

Subtract

3

from both sides

3 + 2 sin (θ + \frac{π}{4}) - 3 = 0 - 3

Simplify

2 sin (θ + \frac{π}{4}) = - 3

2 sin (θ + \frac{π}{4}) = - 3

Divide both sides by

2

2 sin (θ + \frac{π}{4}) = - 3

Divide both sides by

2

\frac{2 sin ( θ + \frac{π}{4} )}{2} = \frac{- 3}{2}

Simplify

sin (θ + \frac{π}{4}) = - \frac{3}{2}

sin (θ + \frac{π}{4}) = - \frac{3}{2}

General solutions for

sin (θ + \frac{π}{4}) = - \frac{3}{2}

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}

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

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

Solve

θ + \frac{π}{4} = \frac{4 π}{3} + 2 πn : θ = 2 πn + \frac{13 π}{12}

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

Move

\frac{π}{4}

to the right side

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

Subtract

\frac{π}{4}

from both sides

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

Simplify

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

Simplify

θ + \frac{π}{4} - \frac{π}{4} : θ

θ + \frac{π}{4} - \frac{π}{4}

Add similar elements:

\frac{π}{4} - \frac{π}{4} = 0

= θ

Simplify

\frac{4 π}{3} + 2 πn - \frac{π}{4} : 2 πn + \frac{13 π}{12}

\frac{4 π}{3} + 2 πn - \frac{π}{4}

Group like terms

= 2 πn - \frac{π}{4} + \frac{4 π}{3}

Least Common Multiplier of

4, 3 : 12

4, 3

Least Common Multiplier (LCM)

Prime factorization of

4 : 2 \cdot 2

4

4

divides by

24 = 2 \cdot 2

= 2 \cdot 2

Prime factorization of

3 : 3

3

3

is a prime number, therefore no factorization is possible

= 3

Multiply each factor the greatest number of times it occurs in either

4

3

= 2 \cdot 2 \cdot 3

Multiply the numbers:

2 \cdot 2 \cdot 3 = 12

= 12

Adjust Fractions based on the LCM

Multiply each numerator by the same amount needed to multiply its

corresponding denominator to turn it into the LCM

12

For

\frac{π}{4} :

multiply the denominator and numerator by

3

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

For

\frac{4 π}{3} :

multiply the denominator and numerator by

4

\frac{4 π}{3} = \frac{4 π 4}{3 \cdot 4} = \frac{16 π}{12}

= - \frac{π 3}{12} + \frac{16 π}{12}

Since the denominators are equal, combine the fractions:

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

= \frac{- π 3 + 16 π}{12}

Add similar elements:

- 3 π + 16 π = 13 π

= 2 πn + \frac{13 π}{12}

θ = 2 πn + \frac{13 π}{12}

θ = 2 πn + \frac{13 π}{12}

θ = 2 πn + \frac{13 π}{12}

Solve

θ + \frac{π}{4} = \frac{5 π}{3} + 2 πn : θ = 2 πn + \frac{17 π}{12}

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

Move

\frac{π}{4}

to the right side

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

Subtract

\frac{π}{4}

from both sides

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

Simplify

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

Simplify

θ + \frac{π}{4} - \frac{π}{4} : θ

θ + \frac{π}{4} - \frac{π}{4}

Add similar elements:

\frac{π}{4} - \frac{π}{4} = 0

= θ

Simplify

\frac{5 π}{3} + 2 πn - \frac{π}{4} : 2 πn + \frac{17 π}{12}

\frac{5 π}{3} + 2 πn - \frac{π}{4}

Group like terms

= 2 πn - \frac{π}{4} + \frac{5 π}{3}

Least Common Multiplier of

4, 3 : 12

4, 3

Least Common Multiplier (LCM)

Prime factorization of

4 : 2 \cdot 2

4

4

divides by

24 = 2 \cdot 2

= 2 \cdot 2

Prime factorization of

3 : 3

3

3

is a prime number, therefore no factorization is possible

= 3

Multiply each factor the greatest number of times it occurs in either

4

3

= 2 \cdot 2 \cdot 3

Multiply the numbers:

2 \cdot 2 \cdot 3 = 12

= 12

Adjust Fractions based on the LCM

Multiply each numerator by the same amount needed to multiply its

corresponding denominator to turn it into the LCM

12

For

\frac{π}{4} :

multiply the denominator and numerator by

3

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

For

\frac{5 π}{3} :

multiply the denominator and numerator by

4

\frac{5 π}{3} = \frac{5 π 4}{3 \cdot 4} = \frac{20 π}{12}

= - \frac{π 3}{12} + \frac{20 π}{12}

Since the denominators are equal, combine the fractions:

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

= \frac{- π 3 + 20 π}{12}

Add similar elements:

- 3 π + 20 π = 17 π

= 2 πn + \frac{17 π}{12}

θ = 2 πn + \frac{17 π}{12}

θ = 2 πn + \frac{17 π}{12}

θ = 2 πn + \frac{17 π}{12}

θ = 2 πn + \frac{13 π}{12}, θ = 2 πn + \frac{17 π}{12}

2 (cos (θ) + sin (θ)) - 3 = 0 : θ = 2 πn + \frac{π}{12}, θ = 2 πn + \frac{5 π}{12}

2 (cos (θ) + sin (θ)) - 3 = 0

Rewrite using trig identities

2 (cos (θ) + sin (θ)) - 3

sin (θ) + cos (θ) = 2 sin (θ + \frac{π}{4})

sin (θ) + cos (θ)

Rewrite as

= 2 (\frac{1}{2} sin (θ) + \frac{1}{2} cos (θ))

Use the following trivial identity:

cos (\frac{π}{4}) = \frac{1}{2}

Use the following trivial identity:

sin (\frac{π}{4}) = \frac{1}{2}

= 2 (cos (\frac{π}{4}) sin (θ) + sin (\frac{π}{4}) cos (θ))

Use the Angle Sum identity:

sin (s + t) = sin (s) cos (t) + cos (s) sin (t)

= 2 sin (θ + \frac{π}{4})

= - 3 + 22 sin (θ + \frac{π}{4})

- 3 + 22 sin (θ + \frac{π}{4}) = 0

Apply radical rule:

a a = a

22 = 2

- 3 + 2 sin (θ + \frac{π}{4}) = 0

Move

3

to the right side

- 3 + 2 sin (θ + \frac{π}{4}) = 0

Add

3

to both sides

- 3 + 2 sin (θ + \frac{π}{4}) + 3 = 0 + 3

Simplify

2 sin (θ + \frac{π}{4}) = 3

2 sin (θ + \frac{π}{4}) = 3

Divide both sides by

2

2 sin (θ + \frac{π}{4}) = 3

Divide both sides by

2

\frac{2 sin ( θ + \frac{π}{4} )}{2} = \frac{3}{2}

Simplify

sin (θ + \frac{π}{4}) = \frac{3}{2}

sin (θ + \frac{π}{4}) = \frac{3}{2}

General solutions for

sin (θ + \frac{π}{4}) = \frac{3}{2}

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}

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

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

Solve

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

θ + \frac{π}{4} = \frac{π}{3} + 2 πn

Move

\frac{π}{4}

to the right side

θ + \frac{π}{4} = \frac{π}{3} + 2 πn

Subtract

\frac{π}{4}

from both sides

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

Simplify

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

Simplify

θ + \frac{π}{4} - \frac{π}{4} : θ

θ + \frac{π}{4} - \frac{π}{4}

Add similar elements:

\frac{π}{4} - \frac{π}{4} = 0

= θ

Simplify

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

\frac{π}{3} + 2 πn - \frac{π}{4}

Group like terms

= 2 πn + \frac{π}{3} - \frac{π}{4}

Least Common Multiplier of

3, 4 : 12

3, 4

Least Common Multiplier (LCM)

Prime factorization of

3 : 3

3

3

is a prime number, therefore no factorization is possible

= 3

Prime factorization of

4 : 2 \cdot 2

4

4

divides by

24 = 2 \cdot 2

= 2 \cdot 2

Multiply each factor the greatest number of times it occurs in either

3

4

= 3 \cdot 2 \cdot 2

Multiply the numbers:

3 \cdot 2 \cdot 2 = 12

= 12

Adjust Fractions based on the LCM

Multiply each numerator by the same amount needed to multiply its

corresponding denominator to turn it into the LCM

12

For

\frac{π}{3} :

multiply the denominator and numerator by

4

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

For

\frac{π}{4} :

multiply the denominator and numerator by

3

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

= \frac{π 4}{12} - \frac{π 3}{12}

Since the denominators are equal, combine the fractions:

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

= \frac{π 4 - π 3}{12}

Add similar elements:

4 π - 3 π = π

= 2 πn + \frac{π}{12}

θ = 2 πn + \frac{π}{12}

θ = 2 πn + \frac{π}{12}

θ = 2 πn + \frac{π}{12}

Solve

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

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

Move

\frac{π}{4}

to the right side

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

Subtract

\frac{π}{4}

from both sides

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

Simplify

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

Simplify

θ + \frac{π}{4} - \frac{π}{4} : θ

θ + \frac{π}{4} - \frac{π}{4}

Add similar elements:

\frac{π}{4} - \frac{π}{4} = 0

= θ

Simplify

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

\frac{2 π}{3} + 2 πn - \frac{π}{4}

Group like terms

= 2 πn - \frac{π}{4} + \frac{2 π}{3}

Least Common Multiplier of

4, 3 : 12

4, 3

Least Common Multiplier (LCM)

Prime factorization of

4 : 2 \cdot 2

4

4

divides by

24 = 2 \cdot 2

= 2 \cdot 2

Prime factorization of

3 : 3

3

3

is a prime number, therefore no factorization is possible

= 3

Multiply each factor the greatest number of times it occurs in either

4

3

= 2 \cdot 2 \cdot 3

Multiply the numbers:

2 \cdot 2 \cdot 3 = 12

= 12

Adjust Fractions based on the LCM

Multiply each numerator by the same amount needed to multiply its

corresponding denominator to turn it into the LCM

12

For

\frac{π}{4} :

multiply the denominator and numerator by

3

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

For

\frac{2 π}{3} :

multiply the denominator and numerator by

4

\frac{2 π}{3} = \frac{2 π 4}{3 \cdot 4} = \frac{8 π}{12}

= - \frac{π 3}{12} + \frac{8 π}{12}

Since the denominators are equal, combine the fractions:

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

= \frac{- π 3 + 8 π}{12}

Add similar elements:

- 3 π + 8 π = 5 π

= 2 πn + \frac{5 π}{12}

θ = 2 πn + \frac{5 π}{12}

θ = 2 πn + \frac{5 π}{12}

θ = 2 πn + \frac{5 π}{12}

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

Combine all the solutions

θ = 2 πn + \frac{13 π}{12}, θ = 2 πn + \frac{17 π}{12}, θ = 2 πn + \frac{π}{12}, θ = 2 πn + \frac{5 π}{12}

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