How Egyptians Built Pyramids with Such Incredible Accuracy

Secant Cosine Tangent Sine 3.14159 Yeah, that was the cheer we heard coming from the trigonometry club back in the day. For the rest of us in math class, terms such as sine, tangent, and pi were just bewildering. Who invented these, and why? Was their only purpose to make it harder for students? Well, not quite. Trigonometry was invented by the ancient Egyptians. They needed this knowledge to construct pyramids, and they did a pretty good job too. The Great Pyramid in Giza still stands today, some 4,500 years after it was built. No recalls either. So let's get out of that classroom and on a journey through time to reveal the secrets behind the ancient Egyptians' precision. Here you are, standing on the Great Pyramid's construction site, some 9 miles from Cairo. Well, the city still isn't there, as you're surrounded only by the desert and teams of construction workers. They're transporting large stone blocks weighing 2.5 tons each. They're inside a wooden sled that sits on large rollers. A crew of 8 men rolls these blocks along the ground. You immediately think of the rollers on a supermarket cash register. The principle is exactly the same, but the scale is greater, much greater. Scientists estimate that the Egyptians used 2.3 million such blocks in the Great Pyramid alone. And the block in front of you is one of the lighter ones. The heaviest of them weighed up to 15 tons. But where did all these blocks come from? Most of them originated from quarries around Giza. It's not that impressive, you think. But wait until you hear how ancient engineers transported the granite used in construction over 500 miles to the pyramid. There were no railways or highways back then, but the mighty Nile was always there. Researchers even believe that the Egyptians dug a canal to connect the Nile directly to the pyramid's construction site. All they had to do then was to wait for the flood season to begin, and voila! The rising water levels floated the heavy stone blocks for them. But how did they lift the enormous stones on dry land to stack them up to the top? Did they use oversized cranes? Well ancient Egyptians worked around this problem, literally speaking. One of the workers is now pointing to the giant ramp going around the pyramid they're building. This is how a mountain road zigzags its way to the top. If the ramp went directly to the top of the pyramid, then workers couldn't pull the stone blocks along it – it would be too steep. Scientists have calculated that 8% could be the maximum incline. So ancient Egyptians just extended the ramp around the pyramid. Again, these are all theories, as the ramp could've been inside the pyramid, as some researchers suggest. The exact building method is still a mystery, guarded by the Sphinx. That's its real name, right? Wrong. As the Great Sphinx is just the statue's alias – you know, the name writers take when they want to hide their true identity – or a singer's stage name. The Sphinx's real name, translated from Egyptian, means Horus in the horizon. That was the name for the Egyptian deity of the sky. The trail of mystery doesn't end there. As a man walks past you with a bucket of paint, he's going to add a touch of color to the Great Sphinx. Researchers found specks of this red color next to its ear. That was some strong paint, as it survived for thousands of years. You are now standing straight in front of the Sphinx. You look up. It's very tall, right? 66 feet to be precise. Now resist the urge to take a selfie. You can do it! Now you notice something else. It looks like the Sphinx is in the center of a giant triangle in the back. That's one side of the Great Pyramid. And no, your eyes are not playing tricks on you. The Sphinx really does sit in the center of the pyramid's lateral face. Here's where math comes in handy. A pyramid has four sides, called lateral faces. There's also a fifth face, the base. But that's not visible. It's – wait for it – face down. The Sphinx has one last mystery to reveal – its age. Scientists agree that Pharaoh Khafre built the Sphinx. He ruled after his father, who had built a Great Pyramid nearby. So both structures were finished around the same time. Let's talk about numbers again. You've heard of Cleopatra, the Egyptian princess described as a woman of great beauty. She saw the pyramids, but she lived closer to the time of the first iPhone than the time of the people who built the pyramids. Fascinating, right? You can see thousands of people around you. They're working hard to build the Pharaoh's tomb. But how many of them are there exactly? One Greek philosopher estimated there were as many as 100,000 workers. Seems like an okay number for such an enormous structure. But it can't be true. Science simply can't back up this number. Egyptologists put the total number of workers at 30,000. And yes, Indiana Jones was one of them, at least on the big screen. But he showed up late. Egyptologists know a lot about the pyramids, but not everything. Not because they don't want to, but because they haven't yet dug up enough evidence. They can only guess how the building process went. First engineers would arrive to choose the right spot and do the necessary measurements. That's why they needed all that complicated math. Then it's time for sourcing the material, the large stone blocks I mentioned earlier. When boats deliver them to the site of the future pyramid, workers can finally do their thing. They operated in smaller groups, but there were at least 2,000 of them chiseling and carving away at any given time. Sounds like a typical construction site today. Well, that's because it is. Just thousands of years ago. It's amazing what ancient Egyptians were able to achieve with just copper and stone tools. The pyramid is now complete in front of you. But is it the same pyramid we see today? Why is this structure shining bright in the desert sun? Isn't it supposed to be a dusty yellow color? Well, no. Human activity and the elements have completely stripped the outer layer of stones over time. Expert craftspeople polished these blocks using nothing but stone and sand. The end result was a smooth and shiny rock. On the day it was completed, the Great Pyramid of Giza was a perfect triangle of light. Its polished sides acted like giant mirrors, reflecting the powerful Egyptian sun. This is the point where you should put your glasses on, and that shiny thing you see at the pyramid's very top is actually gold. The capstone at the top of the pyramid is called a pyramidion. It was covered in sheets of gold. As you can guess, these were the first stones to disappear. Let's make another stop before we get you back to your classroom. We travel to the British Isles, and no, Stonehenge isn't our destination. It is Newgrange in County Meath. Scientists estimate that the ancient peoples of Ireland built this stone monument around the year 3200 BCE. This makes it older than both Stonehenge and the Great Pyramid in Giza. The function of the circular mound in Newgrange is the same as the one of the Great Pyramid and equally mysterious. The estimated amount of loose stone present in the valley is over 220,000 tons. And it's not just randomly thrown on a pile. The order in which the stones are set makes the structure water-resistant. That would explain how Newgrange had survived for so long. Kinda makes you want to splash out the cash for that waterproof phone case, huh? Well, you're back in your school desk, but today's math lecture is the last thing on your mind. You're thinking about how great the Egyptian pyramids are, and if we have something similar today. It turns out modern engineers are just as impressed with the Great Pyramid as you are. There's a glass pyramid sitting in the main courtyard of the famous Louvre Museum in Paris. The panorama of San Francisco wouldn't be complete without the 48-story Transamerica Pyramid. But Las Vegas went the furthest. There we find the Luxor Hotel. It's so big that it's the third-largest pyramid on the planet. And guess what's in front of it? Yep, a replica of the Sphinx. It's 110 feet tall, 2 stories higher than the one in Giza. Yeah, everything's bigger in Vegas. That's it for today! So, hey, if you pacified your curiosity, then give the video a like and share it with your friends. Or if you want more, just click on these videos and stay on the Bright Side!