Depending on your experience in school, there are two ways you might wind up wrestling with an angle.
The first way to "wrestle with an angle" applies to those who take up Freestyle, Greco-Roman, or Jiu-Jitsu with some ulterior motive. It might be impress a potential romantic partner. It might be to avoid having to participate in some other sport. Then again, it might also describe those who get into professional wrestling, where their act / character is how they "wrestle with an angle." Pro tip: unless you
actually want to wrestle, those ulterior motives aren't worth it. It takes sincere interest to put up with mat burns, not to mention having an armpit wrapped around your face while someone tries to connect your tailbone to your eyebrows.
Another other way to "wrestle with an angle" is to struggle with trigonometry or some aspects of mechanical engineering. Even the nerdiest math nerds who are nerdlike sometimes get their sines crossed. Stress or fatigue can make someone go off on a tangent—even cosine on someone's student loan! Occasionally, a rookie mathematician will wrestle with an angle because they got drunk chugging root beer out of a square glass. Look those up or ask someone who looks like a math dork.
Famously, the patriarch of Israel, Jacob, wrestled with an angle while he
wrestled with an angel. He wasn't the geometry type, but he was a schemer. Even when he got his hip socket blown out, he wouldn't let go until he got something out of the encounter. That's not just wrestling with an angle, it's wrestling with
commitment.