How did they find out the height of Everest?

Everest (Chomolungma) is the highest peak of the Earth - 8848 meters above sea level. But how was its height measured?

According to an old legend, when the Welsh geodesist and geographer Sir George Everest measured the height of Mount Chomolungma, he came up with exactly 29,000 feet (8,839.2 meters), and his team decided to add two feet to their measurement to make it more believable. It was believed that the giant mountain rose quietly, secluded from everything else, at 29,002 feet above sea level.

Subsequently, the emergence of sophisticated technologies such as satellites estimated the height of the peak at 29,029 feet (8,848.04 meters). However, Sir Everest's discovery is extremely remarkable considering that he did it in 1852 without the aid of the tools geographers are now equipped with.

What's more, his team took measurements more than 100 miles from the peak as the government of Nepal did not allow the British to enter their country. So how did they reach this amazing calculation?

Trigonometry. The method that geographers rely on is not far from the use of rulers. In fact, Sir Everest and his team applied school geometry to measure the height of Mount Everest. Yes, that's right, only their instruments were just fancier, more complex sets of rulers and protractors.

Trigonometry was used by the Greeks to measure tall structures and by Victorian geodesists to measure the highest mountains before we used satellites. However, even satellites measure altitude, they essentially implement the same principle - they draw triangles.

Triangles. Geographers measure height by drawing numerous triangles. Among the three sides, one is the height of the mountain to be measured. The base of the triangle is between the base of the mountain and a point, say, which is a known distance from the base of the mountain. The third side can be formed by simply connecting point A and the vertex.

When forming a horizontal base, geographers must ensure that it is fully aligned to achieve accurate results. Measuring of any irregularities on the Earth's surface is achieved with very fine instruments. Next, they should measure all three angles formed inside the triangle.

This is accomplished by using a pre-protractor known as theodolite. Measuring even two angles is sufficient, since the third angle can be calculated by subtracting the sum of two known angles from 180 degrees, since the sum of all three angles enclosed by a triangle is 180 degrees.

Now you can understand the magic of a simple trigonometric miracle - knowing two angles and the length of one side can reveal the height of a mountain. Even the ancient Greeks measured height by "comparing the ratios of the two sides of a triangle."

For example, let’s consider a very simple example where the angle formed at point A is 60 degrees, and we only know the distance between point A and the base of the mountain, which of course is the base of the triangle.

For simplicity, let's assume that we are talking about right triangle with the base perpendicular to the height. This means that the third angle formed at the top is 30º (180º- [90º + 60º]). Let's also define the sides of the triangle. Starting at the height and moving clockwise, let's label them as X, Y and Z.

Now Sine Sin (60º) represents the X / Y ratio, while Sin (30º) represents the Z / Y ratio. If we separate these ratios, notice that the two Ys cancel out and we are left with only the X / Z ratio.

The values ​​of both 60º and 30º sines can be found simply by referring to a high school math textbook. In addition, Z is the base of the triangle, the value of which we already know. Multiply Z with Sine ratios and we have the height of the mountain - X.

George Everest drew several of these triangles, all with different distances A, since measurements of one triangle cannot be trusted. The team then averaged each height obtained from all the triangles.

This resulted in a reading of 29,000 feet, a number rumored to have been increased to avoid any suspicion.

Later, in 1999, scientists measured the height of Everest as 8,848 meters above average sea level using satellites.

The accuracy of George Everest's measurements turned out to be amazing - the true height of the peak was only 8.23 meters higher than he predicted. And this was made using only two corners and one side!