Question

3 cos 2x + Sinx = 1 for0° ≤x ≤ 360​

Answer 1

Answer:

x = 41.81°, 138.19°, 210°, 330°

Explanation:

3cos(2x) + sin(x) = 1

subtract one from both sides

→ 3cos(2x) + sin(x) − 1 = 0

rewrite using trigonometry identities

→ 2 + sin(x) − 6sin²(x) = 0

solve x by substitution

f(x) = 2 + sin(x) − 6sin²(x)

= 2 + 4sin(x) - 3sin(x) − 6sin²(x)

= −2sinx(3sinx −2) − (3sinx−2)

= (3sinx −2)(−2sinx−1)

= −(3sinx −2)(2sinx+1)

f(x) = 2 + sin(x) − 6sin²(x) = 0

= −(3sinx −2)(2sinx+1) = 0

(3sinx −2) = 0 (2sinx+1) = 0

→sinx = 2/3 →sinx = −1/2

x = 41.81°, 138.19° x = 210°, 330°

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