趋势线入门：你交易工具中最被低估的工具

If you’ve spent any time on a trading chart, you’ve probably seen those diagonal lines connecting price highs and lows. Those are trend lines—and honestly, they’re one of the simplest yet most effective ways to spot where the market’s actually headed.

Breaking It Down: What Are Trend Lines?

Think of trend lines as the diagonal cousins of support and resistance. Instead of horizontal lines, they’re drawn at an angle to connect multiple price points on a chart. A trend line that slopes upward (connecting lower lows) shows buying pressure is winning. One that slopes downward (connecting higher highs) shows selling pressure is in control. The steeper the angle, the stronger the trend—it’s that straightforward.

There are only two types:

• Uptrend lines: Connect the lows, drawn bottom-left to top-right
• Downtrend lines: Connect the highs, drawn top-left to bottom-right

How to Actually Use Them

Trend lines do two main things. First, they show you support (for uptrends) or resistance (for downtrends)—basically where price tends to bounce back. Second, you can extend them into the future to predict where price might test again.

Here’s the key insight: an uptrend line rising means more buyers than sellers (demand > supply). A downtrend line falling means the opposite. But—and this matters—watch the trading volume too. If price goes up but volume’s tanking, that “uptrend” might be fake.

What Makes a Trend Line Actually Valid?

This is where most traders mess up. Technically you can connect any two dots, but pros agree: you need at least 3 touch points to call it valid. Think of it like this—if price bounces off your trend line once, it could be random. If it does it three times? That’s a real trend, not just coincidence.

The Scale Thing Everyone Forgets

Here’s a dirty little secret: the same trend line can look totally different depending on your chart settings. Arithmetic charts show price changes uniformly (so a $5→$10 move and a $120→$125 move take up equal space). Semi-log charts show percentage moves (so that 100% gain takes way more space than a 4% gain). Pick the wrong scale and your trend line analysis falls apart. Choose wisely.

Real Talk: They’re Not Magic

Trend lines are useful, but they’re not foolproof. Different traders will draw them slightly differently—some connect candle bodies, others use wicks. That subjectivity matters. So don’t just rely on trend lines alone. Combine them with other TA tools like RSI, MACD, moving averages, or Bollinger Bands to actually reduce risk and catch signals other people miss.