Math textbook attempts to solve relationship drama

The correct answer is that Brian and Angela just need to break up, already.

From Thanks, Textbooks — a fantastic Tumblr of supremely weird and hilarious textbook examples and questions.


  1. I think a(t)=√(2)sin(t+pi/4) and b(t)=√(2)cos(t+pi/4). The answer to (d), of course, is Brian.

    1. Actually, the things the student is asked to show are unprovable. If
        a = c sin (q)
        b = c cos(q)
      then all of the conditions are met, but we know nothing about the relation between q and t. In other words, it’s one equation in two unknowns. Therefore, we can’t find the time derivatives without more information.

      1. You missed that b'(t) = -a(t) gets added as a second premise. That’s what really ruins the relationship, romantic comedies notwithstanding.

  2. An exercise in circular reasoning….

    … Which means that they will like each other a quarter of the time for all eternity.  Moreover, they can predict when the quarter of the time when they will dislike each other, and so plan for this while they are on good terms.

    Looks like a better basis for a relationship than many…..

    1. If one or both of them can find a job the requires predictable and compatible times away from home (working in a lumber camp two weeks on / one week off, that kind of thing), it could be a thing of beauty.

      I didn’t actually do the math – what is the cycle length?  Would the requisite job schedule in fact be incredibly weird?

      1. Shay Guy got the math basically right, so this couple goes through an entire cycle roughly weekly.

        That is one high drama couple.

  3. Of course, as any moron with a PhD mathematics could see, the same mathematical equations presented here could model a predator-prey relationship.

    1. The use of predator-prey model for a romantic relationship is decidedly odd. Do you mis-understand what a woman typically means where she says  “My boyfriend eats me”  ?

  4. I think the lesson for me here is to finally forego mathematics as means in understanding one’s boyfriend/girlfriend/husband/spouse (singular/multiple) …mine and/or someone else’s…

  5. I think this math problem is a reference to a paper by Sergio Rinaldi  that attempted to do a similar mathematical analysis of the unrequited love of Petrach for Laura by analyzing Petrarch’s poems. 

    That analysis also results in a cyclical love dynamic (the name of my new band), though since it was unrequited the cycles were mostly Petrarch’s.  

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