when the trend is up and the price stays in the space above an ascending angle without breaking below it the market is regarded as strong when the trend is down and the price remains below a descending angle without breaking above it the market is considered weak depending on which angle it is respecting shows the overall strength or weakness of the trend 
the idea is that if the price passes through one angle the price may be heading toward the next gann fans have been applied to a chart of the spdr dow jones industrial average etf dia the first angles were drawn off the late 2018 low angle 1 1 is drawn at a 45 degree angle over time the uptrend gradually began respecting the 3 1 angle the price then dropped further as the price declines it eventually breaks through all the up trending angles at any time during the decline gann angles can also be applied to the high price point descending lower 1 1 is once again aligned with 45 degrees an angle tool may be used to make sure that 1 1 is at 45 degrees the difference between gann angles and trendlinesgann angles are drawn at specific angles regardless of how the price moves trendlines connect swing lows to swing lows and swing highs in price to swing highs the indicators are providing different information gann angles were not meant to be drawn along price action they are independent of it limitations of using gann anglesgann created his own charts creating his own scales for time and price movements most charting platforms today auto scale data to fit the screen provided while a 45 degree can be drawn on any chart if someone has a different scale numbers showing on the x or y axis their angles will intersect at different time and price points therefore every trader unless their charts are identically scaled will have different angles this means the indicator is subject to great subjectivity this indicator is not particularly useful for actual trade signals indeed the price often does not proceed directly if at all to the next gann angle once an angle is broken 