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A triangle has sides 4, 5 and 7. Which statement about it is correct?
AIt is acute-angled
BIt is right-angled
CIt is obtuse-angled
DIt is equilateral
Answer & Solution
Correct answer: C. It is obtuse-angled
16 + 25 = 41 is less than 49, so cos of the angle facing side 7 is negative.
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