# What were epicycles used to describe?

## What were epicycles used to describe?

In the Hipparchian, Ptolemaic, and Copernican systems of astronomy, the epicycle (from Ancient Greek: ἐπίκυκλος, literally upon the circle, meaning circle moving on another circle) was a geometric model used to explain the variations in speed and direction of the apparent motion of the Moon, Sun, and planets.

1,737.1 km

## Which of the following is 250000 stadia equal to?

Taking the Earth as spherical, the Earth’s circumference would be fifty times the distance between Alexandria and Syene, that is 250,000 stadia. Since 1 Egyptian stadium is equal to 157.5 metres, the result is 39,375 km, which is 1.6% less than the real number, 40,008 km.

24,662 miles

## How did Eratosthenes measure angles?

Eratosthenes could measure the angle of the Sun’s rays off the vertical by dividing the length of the leg opposite the angle (the length of the shadow) by the leg adjacent to the angle (the height of the pole). This gave him an angle of 7.12 degrees.

## What is equatorial circumference?

The distance around the Earth at the Equator, its circumference, is 40,075 kilometers (24,901 miles). The Earth’s diameter is also wider at the Equator, creating a phenomenon called an equatorial bulge.

155,600 km

## Is circumference and perimeter of circle same?

Perimeter or Circumference. This is the total length of a shape’s outline. The length of a straight-sided shape’s outline is called its perimeter, and the length of a circle’s outline is called its circumference.

## Why is circumference divided by diameter equal to pi?

Dividing the circumference of a circle by its diameter will always give pi because that’s how pi is defined. “By definition, pi is the ratio of the circumference of a circle to its diameter. Pi is always the same number, no matter which circle you use to compute it. ” As stated, Pi is a result, not a cause.