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Using the follo w in g figure, show that BD = x. - Mathematics

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Question

Using the following figure, show that BD = `sqrtx`.

Numerical

Solution

AB = x and BC = 1

AC = AB + BC

= x + 1

diameter = x + 1

radius OA = OD = OC = OB = OC - BC

`= (x + 1)/2 - 1 = (x + 1 -2)/2 = (x - 1)/2`

Using pythagoras in ΔBOD

P2 + B2 = H2

`"P"^2 + ((x - 1)/2)^2 = ((x + 1)/2)^2`

`"P"^2 = ((x + 1)/2)^2 - ((x - 1)/2)^2`

= `((x + 1)^2 - (x - 1)^2)/4`

`= ((x^2 + 1 + 2x) - (x^2 + 1 - 2x))/4`

`= (x^2 + 1 + 2x - x^2 - 1 + 2x)/4`

`"P"^2 = (4x)/4`

P2 = x

P = `sqrtx`

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Simplifying an Expression by Rationalization of the Denominator
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Chapter 1: Rational and Irrational Numbers - Exercise 1 (D) [Page 23]

APPEARS IN

Selina Concise Mathematics [English] Class 9 ICSE
Chapter 1 Rational and Irrational Numbers
Exercise 1 (D) | Q 13. | Page 23
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