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In ∆ABC, if AB = 16 cm, BC = 12 cm and AC = 20 cm, then ∆ABC is (a) acute-angled (b) right-angled (c) obtuse-angled |
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Answer» (b) right-angled We have: AB2 + BC2 = 162 + 122 = 256 + 144 = 400 and, AC2 = 202 = 400 ∴ AB2 + BC2 = AC2 Hence, ∆ABC is a right-angled triangle. |
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