Three moons are in the same circular orbit around a planet. The moons are each 120,000 kilometers from the surface of the planet, located at points A, B, and C. The planet is 60,000 kilometers in diameter and m∠ABC=90∘. How far is point A from point C?
The diameter of the orbit is 60,000 + 2·120,000 km = 300,000 km. The 90° angle at B must subtend an arc of 180° of that circle. That places points A and C on the ends of a diameter, hence 300,000 km apart.
