Definition: Concurrent Straight Lines
Different straight lines which passes through the same point are said to be concurrent. We also say that concurrent straight lines $l_1,l_2,\ldots$ meet at the point $A$ and write $$P=l_1\cdot l_2\cdot\ldots.$$
We agree that the order of the lines in this dot “$\cdot$” notation does not play any role, e.g. $m\cdot l$ and $l\cdot m$ for two straight lines $m$ and $l$ denote the same point. Please note the difference of notation of concurrent lines and collinear points, where we do not use the dot “$\cdot$”.
The following figure shows an example of four coincident straight lines passing a point $A=k\cdot l\cdot m\cdot n.$
| | | | | created: 2018-04-23 22:07:04 | modified: 2018-04-23 23:17:07 | by: bookofproofs