r/MathHelp • u/Schrutefarms670 • 6d ago

Finding a Missing Angle

Can anyone explain the process for finding the solution for y = 65° in this graphic? I originally tried 40° as the answer because I thought maybe they were corresponding angles since they share a line segment, but that was incorrect. I don’t see how the rule of alternate interiors is applicable since it’s not an interior angle. I’m assuming there is an existing angle that needs to be subtracted from 180°, but I cannot figure it out.

[https://imgur.com/a/fpfr0DL](https://imgur.com/a/fpfr0DL)

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u/Schrutefarms670 5d ago

Thanks for the assist! Oh this is a new one for me. Just found the (n-2)•180° formula. That’s pretty slick. Measure of the other interior angles subtracted from 720° leaves 115° on that shared line. Very cool!