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Question
In the right-angled ∆LMN, ∠M = 90°. If l(LM) = 12 cm and l(LN) = 20 cm, find the length of seg MN.
Solution
In the right-angled triangle LMN, ∠M = 90°. Hence, side LN is the hypotenuse.
According to Pythagoras' theorem,
l(LN)2 = l(MN)2 + l(LM)2
⇒ (20)2 = l(MN)2 + (12)2
⇒ 400 = l(MN)2 + 144
⇒ l(MN)2 = 400 − 144
⇒ l(MN)2 = 256
⇒ l(MN)2 = (16)2
⇒ l(MN) = 16
∴ Length of seg MN = 16 cm.
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