A triangle is a chart pattern formed by drawing trendlines on a converging price range. There are three different types of triangle patterns, ascending, descending and symmetrical. Triangles are very useful to determine continuation/reversal trends.
An ascending triangle is a breakout pattern that forms when the price breaches the upper horizontal trendline. The upper trendline must be horizontal, indicating nearly identical highs, which form a resistance level. The lower trendline is rising diagonally, indicating higher lows as buyers continue to buy at higher price points until it reaches the resistance level and breaks out.
A descending triangle is an inverted version of the ascending triangle and considered a breakdown pattern. The lower trendline should be horizontal, connecting near identical lows. The upper trendline declines diagonally toward the apex. The breakdown occurs when the price collapses through the lower horizontal trendline support as the downtrend resumes.
A symmetrical triangle is composed of a diagonal falling upper trendline and a diagonally rising lower trendline. As the price moves toward the apex, it will inevitably breach the upper trendline for a breakout and uptrend on rising prices or breach the lower trendline forming a breakdown and downtrend with falling prices.