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In triangle ABC, given below, AB = 8 cm, BC = 6 cm and AC = 3 cm. Calculate the length of OC.

In triangle ABC, given below, AB = 8 cm, BC = 6 cm and AC = 3 cm. Calculate the length of OC. Pythagoras Theorem, Concise Mathematics Solutions ICSE Class 9.

Pythagoras Theorem

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Answer

Let length of OC be x cm.

In right angled triangle AOC,

By pythagoras theorem,

⇒ (Hypotenuse)2 = (Perpendicular)2 + (Base)2

⇒ AC2 = AO2 + OC2

⇒ 32 = AO2 + x2

⇒ AO2 = 32 - x2

⇒ AO2 = 9 - x2

⇒ AO = 9x2\sqrt{9 - x^2} cm.

From figure,

BO = BC + CO = (6 + x) cm.

In right angled triangle AOB,

By pythagoras theorem,

⇒ (Hypotenuse)2 = (Perpendicular)2 + (Base)2

⇒ AB2 = AO2 + BO2

⇒ 82 = (9x2)2(\sqrt{9 - x^2})^2 + (6 + x)2

⇒ 64 = 9 - x2 + 36 + x2 + 12x

⇒ 64 = 45 + 12x

⇒ 12x = 64 - 45

⇒ 12x = 19

⇒ x = 1912=1712\dfrac{19}{12} = 1\dfrac{7}{12}.

Hence, OC = 17121\dfrac{7}{12} cm.

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