1- you have only 2 candles A and B , no need more than that to prove it
2- your strategy is to create a trendline that will pass across A, B close prices
3- infinity opens here when you can create infinite new strategies by setting: trend A= A+10 points trend B= B-20 points, for example, and
there are infinite numbers to test all of them, if that is not enough, you can then say that trend A value will be applied to N position candles in space before candle A, so even small number can
make geometrical difference depending on the position of the trendline, even 0.000001 difference, given the right distance, will make a huge difference.
To one person come and say 100% sure that Technical Analysis doesn't work you have to test all these possibilites, not even a quantum computer no matter the size can do that, so its proved TA do work, because you
can't prove otherwise
MetaTrader 5 Help → Price Charts, Technical and Fundamental Analysis → Analytical Objects → Lines → Trendline :
A trendline is a straight line that joins two important minimal or maximal price lines in a chart. Within a main trend there can be any number of secondary or minor trends. The length of each of them differs within wide ranges. It should be remembered that a trendline must not intersect with other prices between the two selected points. A trendline is a support/resistance pass-through where price changes within the range of the pass-through.
It means the following:
If TA can't work, then no one can make money in the long term. Yet there are many people who do. Thus proving that it does work.