Question: An astronomer observes a planetary orbit modeled as an ellipse with semi-major axis $a = 10$ AU and semi-minor axis $b = 6$ AU. What is the approximate circumference of the elliptical orbit? (Use Ramanujan’s approximation: $C \approx \pi \left[3(a + b) - \sqrt(3a + b)(a + 3b)\right]$.) - Portal da Acústica