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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