Modern mathematical methods have since proved that each of the three classical construction problems listed at the beginning of this section is impossible, but generations of Greek mathematicians tried to find solutions. In the course of their searches, they drew many curves and explored their properties. To solve these problems the rules imposed by Euclid had to be relaxed. You will see one of the ways in which they were relaxed in the work of Archimedes in Chapter 4. Some propositions from Euclid Euclid's Elements consists of a number of separate books. Activities 3.5 and 3.6 will show you how Euclid's arguments are built up. Each book consists of a series of statements, called propositions. Later propositions are proved from the earlier ones. The proof of each proposition is rather like an algorithm, which can then be used in the algorithm for later propositions