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

Timothy Norman

in Mathematics

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Cynthia Baker on December 5, 2018

81^2 = 18 ^2 + 80^6561 = 324 + 64006561 = 6724It is not a right angle, since 18^2 + 80^2 is not equal to 81^2.Thus,Using The law of cosines:The larger angle C is opposite side c. therefore, c^2 = a^2 + b^2 -2ab (cosC) Here, c^2 < (a^2 + b^2) cosC must be positive, which makes C an acute angle.


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