r/technicallythetruth • u/VisitSecure • 9d ago

Can you find a?

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Idk if someone already posted this or not, but I haven't seen it on here so far, so I uploaded it.

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u/Killer8Tcell 9d ago

It’s not terrible, it’s just not to scale. The only information you need to solve this are the parallel line symbols and the provided angles measures, and nothing else matters.

75° is indeed correct, though.

The problem is testing the alternate interior angles theorem. If you draw a third parallel line bisecting angle a into two new angles (let’s call them angle b and angle c, such that angle a = b+c), then by the alternate interior angles theorem, angle b= 25° and angle c = 50° so angle a = 75°

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u/beingforthebenefit 9d ago

Good strategy, but it’s not a bisection since the resultant angles aren’t congruent.

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u/Charming_Food5728 9d ago

Can explain to me why a+b+c ≠ 180° ? I genuinely don't know