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A triangle has side lengths of 16cm, 63cm, and 65cm. Classify it as acute, obtuse or right.

Please helpppp!!!

User Panos
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1 Answer

14 votes
14 votes

9514 1404 393

Answer:

right

Explanation:

If you're going to be in the business of classifying triangles based on side lengths, it can be useful to know there is a "form factor" that can help. For sides a, b, c, with long side 'c', it is computed as ...

f = a² + b² - c²

It has the following interpretation with respect to triangle shape:

f > 0 . . . acute

f = 0 . . . right

f < 0 . . . obtuse

__

In this case, we have ...

16² +63² -65² = 256 +3969 -4225 = 0

The triangle is a right triangle.

_____

Additional comment

When the triangle is a right triangle, this is equivalent to a statement of the Pythagorean theorem: c² = a² + b².

For triangles of other shapes, the interpretation is consistent with the Law of Cosines. When the form factor is divided by 2ab, the result is the cosine of the largest angle. That is why >0 means acute and <0 means obtuse.

User Sireesh Vattikuti
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