The Exception Proves the Rule
A student uses a non-right triangle as 'the exception that proves the rule' that all triangles are right.
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Free for classrooms, worksheets, slides and other non-commercial use under CC BY-NC 4.0, with credit to Ben Orlin.
Cartoon by Ben Orlin, Math with Bad Drawings. https://cartoons.mathwithbaddrawings.com/2019-12-03-the-exception-proves-the-rule/ (CC BY-NC 4.0)Transcript
A (beside a 5-6-7 triangle, "5² + 6² ≠ 7²"): "See? All triangles really do have right angles!" B: "I told you, 'the exception proves the rule' doesn't work in math. Or anywhere."