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Mathematics

In the following figure :

OA = 2 cm = AB = 2BC = 12\dfrac{1}{2} CD = 16\dfrac{1}{6} DE

Find the length of OE.

In the following figure OA = 2 cm = AB = 2BC. Find the length of OE. Chapterwise Revision (Stage 2), Concise Mathematics Solutions ICSE Class 9.

Pythagoras Theorem

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Answer

Given: OA = AB = 2 cm

2BC = 2 cm ⇒ BC = 22\dfrac{2}{2} = 1 cm

12\dfrac{1}{2} CD = 2 cm ⇒ CD = 2 x 2 = 4 cm

16\dfrac{1}{6} DE ⇒ DE = 6 x 2 = 12 cm

In Δ ABO, using Pythagorean theorem,

⇒ BO2 = AB2 + AO2

= (2)2 + (2)2

= 4 + 4

= 8

⇒ BO = 8\sqrt{8} = 2 2\sqrt{2} cm

Similarly, in Δ OBC, using Pythagorean theorem,

⇒ CO2 = OB2 + BC2

= (2 2\sqrt{2})2 + 12

= 8 + 1

= 9

⇒ CO = 9\sqrt{9} = 3 cm

Similarly, in Δ OCD, using Pythagorean theorem,

⇒ DO2 = OC2 + CD2

= 32 + 42

= 9 + 16

= 25

⇒ DO = 25\sqrt{25} = 5 cm

In Δ ODE, using Pythagorean theorem,

⇒ OE2 = OD2 + DE2

= 52 + 122

= 25 + 144

= 169

⇒ OE = 169\sqrt{169} = 13 cm

Hence, the length of OE = 13cm.

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