Problem 8.322
mediumFor the conic \( \displaystyle r = \frac{5}{3 \cos{\left(\theta \right)} + 4} \), find the eccentricity, identify the conic, and find the directrix.
- Divide top and bottom by the constant in the denominator to get r = ed/(1 ± e cos θ).Reviewed
- \[ \frac{5}{4 \left(\frac{3 \cos{\left(\theta \right)}}{4} + 1\right)} = \frac{5}{3 \cos{\left(\theta \right)} + 4} \]The standard form.✓ Proved
- \[ \frac{\left|{3}\right|}{4} = \frac{3}{4} \]e = 3/4: < 1, an ellipse.✓ Proved
- \[ \frac{5}{4 \cdot \frac{3}{4}} = \frac{5}{3} \]ed = 5/4, so d = 5/3.✓ Proved
Answer \( e = \frac{3}{4},\ \text{ellipse},\ \text{directrix } x = 5/3 \)
✓ Nihil obstat Lines: 3 proved, 1 reviewed. The answer was also checked a second way, without looking at the solution. Reviewers found nothing wrong with the explanation. The full receipt · How we verify