Cindy has 89 coins. If 15% are dimes, how many are not
1 answer:
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9514 1404 393
Answer:
C. Obtuse
Step-by-step explanation:
The "form factor" I use for this is ...
a^2 + b^2 - c^2 = 6^2 + 8^2 - 11^2 = 36 +64 -121 = -21
The value is negative, indicating an OBTUSE triangle.
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<em>Additional comment</em>
In this expression, 'a' and 'b' are the two shortest sides (in no particular order) and 'c' is the longest side. The interpretation is ...
negative — obtuse
zero — right
positive — acute
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If you're familiar with Pythagorean triples, you know that the 3-4-5 right triangle triple can be doubled to give 6-8-10. The long side of 11 is longer than the hypotenuse for the right triangle, so would correspond to a largest angle greater than 90°. The 6-8-11 triangle would be OBTUSE.
