if tanθ = \(\frac{3}{4}\), 180° < θ < 270°, find the value of cosθ....
MATHEMATICS
WAEC 2021
if tanθ = \(\frac{3}{4}\), 180° < θ < 270°, find the value of cosθ.
- A. \(\frac{4}{5}\)
- B. \(\frac{3}{5}\)
- C. -\(\frac{4}{5}\)
- D. -\(\frac{3}{5}\)
Correct Answer: C. -\(\frac{4}{5}\)
Explanation
tanθ = \(\frac{3}{4}\) → tanθ = 0.75
θ = tan\(^{-1}\)[0.75] → 36.8698°
cosθ = cos[36.8698°]
→ 0.800 or \(\frac{4}{5}\)
However; in the third quadrant Cosine is negative
i.e -\(\frac{4}{5}\)
Post an Explanation Or Report an Error
If you see any wrong question or answer, please leave a comment below and we'll take a look. If you doubt why the selected answer is correct or need additional more details? Please drop a comment or Contact us directly. Your email address will not be published. Required fields are marked *