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Find the unknown side in the following triangles

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#### Solution

From ∆ABC, by Pythagoras theorem

BC^{2} = AB^{2} + AC^{2}

Take AB^{2} + AC^{2}

= 9^{2} + 40^{2}

= 81 + 1600

= 1681

BC^{2} = AB^{2} + AC^{2}

= 1681

= 41^{2}

BC^{2} = 41^{2}

⇒ BC = 41

∴ x = 41

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