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Solve for the unknown variable. Give all of the exact general solutions.

cosθ = sinθ

1 + sinθ = 2cos^2 (θ)

sin3θ = -1

User Messiah
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Answer:

Solving for the unknown variable:

cosθ = sinθ

Dividing both sides by cosθ, we get:

tanθ = 1

Taking the inverse tangent of both sides, we get:

θ = π/4 + nπ, where n is an integer.

Therefore, the exact general solution is:

θ = π/4 + nπ, where n is an integer.

1 + sinθ = 2cos^2 (θ)

Using the identity cos^2 (θ) + sin^2 (θ) = 1, we can rewrite the equation as:

1 + sinθ = 2(1 - sin^2 (θ))

Expanding the right-hand side, we get:

1 + sinθ = 2 - 2sin^2 (θ)

Rearranging, we get:

2sin^2 (θ) + sinθ - 1 = 0

Using the quadratic formula, we get:

sinθ = (-1 ± √5)/4

Taking the inverse sine of both solutions, we get:

θ = arcsin [(-1 ± √5)/4] + 2nπ or π - arcsin [(-1 ± √5)/4] + 2nπ, where n is an integer.

Therefore, the exact general solution is:

θ = arcsin [(-1 ± √5)/4] + 2nπ or π - arcsin [(-1 ± √5)/4] + 2nπ, where n is an integer.

sin3θ = -1

Taking the inverse sine of both sides, we get:

3θ = (-1)^n (π/2) + 2nπ, where n is an integer.

Dividing both sides by 3, we get:

θ = (-1)^n (π/6) + (2nπ)/3, where n is an integer.

Therefore, the exact general solution is:

θ = (-1)^n (π/6) + (2nπ)/3, where n is an integer.

User Corona Luo
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