A triangle has side lengths of 18 cm, 80 cm, and 81 cm. Classify it as acute, obtuse, or right.

What are the definitions of acute, obtuse and right triangles?

ANGLE -> acute is less than 90 degrees -> obtuse is more than 90 degrees -> right is just 90 degrees.

Try drawing a picture to help yourself out. It doesn't have to be exactly to scale, but if you know 80 and 81 are similar and you have a much smaller side of 18, what might that look like? Try the pythagorean theorem if you feel like there might be a right angle involved.

try it in a software to work out with exact scale. Then you can figure out if the triangle is equilateral, isosceles, scalene, or right-angled. http://en.wikipedia.org/wiki/Triangle#Types_of_triangles

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