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If sin(2x) = cos(x + 30°), what is the value of x?

User Shivid
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1 Answer

1 vote

Answer:

x = -10 ° + π/6 + (2 π n_1)/3 for n_1 element Z

or x = 30 ° + π/2 + 2 π n_2 for n_2 element Z

Explanation:

Solve for x:

sin(2 x) = cos(x + 30 °)

Rewrite the right hand side using cos(θ) = sin(θ + π/2):

sin(2 x) = sin(30 ° + π/2 + x)

Take the inverse sine of both sides:

2 x = -30 ° + π/2 - x + 2 π n_1 for n_1 element Z

or 2 x = 30 ° + π/2 + x + 2 π n_2 for n_2 element Z

Add x to both sides:

3 x = -30 ° + π/2 + 2 π n_1 for n_1 element Z

or 2 x = 30 ° + π/2 + x + 2 π n_2 for n_2 element Z

Divide both sides by 3:

x = -10 ° + π/6 + (2 π n_1)/3 for n_1 element Z

or 2 x = 30 ° + π/2 + x + 2 π n_2 for n_2 element Z

Subtract x from both sides:

Answer: x = -10 ° + π/6 + (2 π n_1)/3 for n_1 element Z

or x = 30 ° + π/2 + 2 π n_2 for n_2 element Z

User Himsara Gallege
by
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