The objective in this turn set is to maximize the exit speed coming out of turn 3. Turn 4 can be taken flat out, so the exit speed coming out of 3 sets the speed through turn 4 and the following lengthy straight. Setting up this series of corners begins with the turn-in to turn 1. Unlike the "normal" racing line, turn 1 is taken with a very late apex to allow the car to stay on the far right side of the track after the turn. This positions the car to take turn 2 in a similar manner with a very late apex keeping the car on the far left side of the track. This finally places the car in the correct position to take turn 3 with a typical racing line. Not only can turn 3 be taken with a typical line, but using this line allows acceleration towards turn 4 to start before turn 3.
This is a classic example of the need to "sacrifice" the highest possible speed in turns 1 and 2 in order to maximize the speed of turn 3 which is more important. Some people do not agree with the term "sacrifice," and would rather call this corner prioritization, or proper "setting up" of turn 3. No matter what you call it, you must analyze corner sets like this to recognize that the fast line is the correct way, and that you must temper you instinct to blast through 1 and 2 as in the "slow" line diagram which puts the car in the completely wrong position for turn 3, and delays the point at which the driver is accelerating for turn 4.
This line might be your first instinct. It carries higher speed into the corner set by taking a normal racing line through turn 1, but immediately forces a scramble through turns 2 and 3 which severely slows the car's speed through turn 4.