Investopedia explains 'Symmetrical Triangle' A symmetrical triangle is generally regarded as a period of consolidation before the price moves beyond one of the identified trendlines. A break below the lower trendline is used by technical traders to signal a move lower, while a break above the upper trendline signals the beginning of a move upward. As you can see from the chart above, technical traders use a sharp increase in volume or any other available technical indicator to confirm a breakout beyond one of the trendlines.