A triangle is a chart pattern, depicted by drawing trendlines along a converging price range that connotes a pause in the prevailing trend. Technical analysts tend to categorize triangles as trend continuation patterns. There are three types of triangles: ascending triangle, descending triangle and symmetrical triangle.
An ascending triangle is a breakout that forms when the price breaches the upper horizontal trendline with rising volume. The upper trendline, acting as the resistance level, must be horizontal; the lower trendline, being the support level, is rising diagonally.
A descending triangle is an inverted version of the ascending triangle and hence considered as a breakdown pattern. The lower support trendline is horizontal while the upper resistance trendline declines diagonally.
A symmetrical triangle is composed of a diagonally falling upper resistance trendline and a diagonally rising lower support trendline. As the price reaches towards the apex, there usually will be either a breakout or breakdown.