The chart displays Blue Standard Error Channel (SEC), White Fibonacci Fan, single Black trendline with pivot points Red circled, Blue Fibonacci Price Levels, Red Gann Fan.
I prefer using the SEC as it projects price movement as a pathway, channel; at the end of the movement the price 'drops out' of the channel confirming the trend end, as well as the price rising and falling within the channel. The Fibo Fan is also quite good provided the 'throw' or distance from the start point produces enough separation of the fan lines. Don't use MetaStock's Gann Fan since the user can't enter angle degrees.
50 cent: "why do they [trendlines] work - why price halts at trendlines?"
From my point of view, trendlines work 'after-the-fact' â after the price has changed direction; why the price halts at a trendline is because it hit a fibo level. The Fibonacci ratio is an elastic constant. First drawn on 'Wave 1' â any W1, that ratio measure appears to remain constant throughout the whole '5 Wave' price movement that follows. Significant price 'turns' throughout the movement appear to occur at fibo price levels rather than not occurring at the fibo levels.
Other trendlines are Murrey Math lines, an adaption of Gann theory - division of the price by 1/8ths related to divisions of the 360 degree circle, Gann's 1/1 1/3 1/4 etc angles:
http://www.murreymathtrading.com/ see also Advanced Get's Gann Box below.