Solution 7 White has one long Sector Line here, and by playing to just break it (a reduction, rather than an invasion), Black satisfied both of his objectives as well as possible in this position. And although it’s not known whether either of these players explicitly used Sector Lines in deciding upon their moves, it’s apparent that B39 was played precisely as though they had!
More important, I’m betting that you, the reader, although perhaps little more than a beginning player, was also able to find this exact move or one very near it, just by applying the simple yet powerful Sector Line concept!