If √5 cosx + √15sinx = 0, for 0° < x < 360°, find the
FURTHER MATHEMATICS
WAEC 2021
If √5 cosx + √15sinx = 0, for 0° < x < 360°, find the values of x.
- A. 30° and 150°
- B. 150° and 210°
- C. 150° and 330°
- D. 210° and 330°
Correct Answer: C. 150° and 330°
Explanation
√5 cosx + √15sinx = 0;
√5 (cosx + √3sinx) = 0
cosx = -sinx√3; \(\frac{sinx}{cos}\) = \(\frac{-1}{√3}\)
tanx = \(\frac{-1}{√3}\); x = 150° or 330°
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