Question

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Answer 1

Answer:

x = 90°

Step-by-step explanation:

Using the identity

cos²x = 1 - sin²x

Given

cos²x - sin x + 1 = 0

1 - sin²x - sin x + 1 = 0

- sin²x - sin x + 2 = 0 ← quadratic equation in sin x ( multiply through by - 1 )

sin²x + sin x - 2 = 0 ← in standard form

(sinx + 2)(sinx - 1) = 0 ← in factored form

Equate each factor to zero and solve for x

sinx + 2 = 0 ⇒ sinx = - 2 ← has no solution as - 1 ≤ x ≤ 1

sinx - 1 = 0 ⇒ sinx = 1 ⇒ x = 90°

solution is x = 90°