Angle trisection an angle of measure 30 degrees). It is possible to trisect an arbitrary angle by using tools other than straightedge and compass. For example, neusis construction, also known to ancient Greeks, involves simultaneous sliding and rotation of a marked straightedge, which cannot be achieved with the original tools. Other techniques were developed by mathematicians over the centuries. Because it is defined in simple terms, but complex to prove unsolvable, the problem of angle trisection is a frequent subject of pseudomathematical attempts at solution by naive enthusiasts. These "solutions" often involve mistaken interpretations of the rules, or are simply incorrect. Using
Less-than sign encoded as a single-byte code point token. In Fortran, operator .LE. means "less than or equal to". In Bourne shell and Windows PowerShell, the operator -le means "less than or equal to". In the R programming language, the less-than sign is used in conjunction with a hyphen-minus to create an arrow (codice_1), this can be used as the left assignment operator. In Bourne shell (and many other shells), less-than sign is used to redirect input from a file. Less-than plus ampersand (<&) is used to redirect from a file descriptor. Less-than sign is used in the spaceship operator. In HTML