Tham khảo tài liệu 'anh ngữ sơ cấp - học tiếng anh bằng hình ành (phần 3) part 6', tài liệu phổ thông, tiếng anh phục vụ nhu cầu học tập, nghiên cứu và làm việc hiệu quả | Sometimes a man s fields were not square. Some of them were like this or like fids. Men walked across theừ fields they planted them and took in the grain. They knew how much land they had from working them before they could measure them. They saw that a field like this was the same size though not the same shape as a field like this before they knew that they could measure how long and how wide a field was and then get the area by taking one measure times the other. will plant pkmt J planted 458 They saw that they could get half a field in this way. or in this way before they knew how to measure rectangles or triangtea- Can you see whether these two fields have the same area Put in lines to prove that they are or are not equal in area. The answer is at the bottom of page 178. roctoagloi a ractangla ba four tfralghi sldM and four right angle . 459 Hero is a right angled triangle. The two shorter sides are three and four units long. How many units long is the longest side Can you tell without measuring How About 2500 years ago 500 . a great Greek Pythagoras proved that the square on the longest side of any right angled triangle is equal to the squares on the other two sides added together. We can use his discovery to get our answer. We multiply the length ot each ot the two shorter sides by itself. We add the answers together. Then we find a number which multiplied by itself gives us this number. .
