The quadrilateral hierarchy
The question
Every parallelogram is a rectangle.
Every parallelogram is a rectangle.
Every parallelogram is a rectangle.
alwayssometimesnever
alwayssometimesnever
sometimes
- One example that works does not prove "always" — but one that fails is enough to disprove it.
- So look for a counter-example: a case where the claim breaks.
- Try a 6 by 6 square — true. Try a slanted rhombus with 13-unit sides — false. One example is not enough. So the answer is sometimes.
How it works.
- 01
One example that works does not prove "always" — but one that fails is enough to disprove it.
- 02
So look for a counter-example: a case where the claim breaks.
- 03
Try a 6 by 6 square — true. Try a slanted rhombus with 13-unit sides — false. One example is not enough. So the answer is sometimes.