# What did Al-Battani discover?

## What did Al-Battani discover?

One of al-Battānī’s best-known achievements in astronomy was the determination of the solar year as being 365 days, 5 hours, 46 minutes and 24 seconds, which is only 2 minutes and 22 seconds off. Another of al-Battānī’s accomplishments is that he concluded how an annular solar eclipse occurs.

**How did Al-Battani calculate the length of the year for kids?**

He cataloged 489 stars. He refined the existing values for the length of the year, which he gave as 365 days 5 hours 46 minutes 24 seconds, and of the seasons. He calculated 54.5″ per year for the precession of the equinoxes and obtained the value of 23° 35′ for the inclination of the ecliptic.

### When was Al-Battani born?

858 AD

Al-Battani/Date of birth

**What kind of math did Al Battani do?**

Al-Battani is one of the famous Muslim scholars of mathematics and planetary studies. He was born in the age known as the Golden Age of Islam. With his deep interest in trigonometry – the branch of math that deals with three sides and three angles, he found relations between trigonometric signs like sine, cosine, and tangent.

## How did Al-Battani solve the equation sin x?

He also solved the equation sin x = a cos x discovering the formula: He gives other trigonometric formulae for right-angled triangles such as: Al-Battānī used al-Marwazi ‘s idea of tangents (“shadows”) to develop equations for calculating tangents and cotangents, compiling tables of them.

**What is the formula for Al Battani’s table of Shadows?**

Al-Battani’s rule, s = h sin (90 0 – θ)/ sin θ, is equivalent to the formula s = h cot θ. Based on this rule, he constructed a ‘table of shadows’ – essentially a table of cotangents – for each degree from 1 0 to 90 0 .” (www.britannica.com)

### What was Al-Battani’s rule for the elevation of the Sun?

“Al-Battani gave a rule for finding the elevation θ of the sun above the horizon in terms of the length s of the shadow cast by a vertical gnomon of height h. Al-Battani’s rule, s = h sin (90 0 – θ)/ sin θ, is equivalent to the formula s = h cot θ.