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The midpoints of the sides of a square of side 1 are joined to form a new square. This procedure is repeated indefinitely. Find the sum of the areas of all the squares

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Question

The midpoints of the sides of a square of side 1 are joined to form a new square. This procedure is repeated indefinitely. Find the sum of the areas of all the squares

Sum
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Solution


Area of the 1st square = 12

Area of the 2nd square = `(1/sqrt2)^2`

Area of the 3rd square = `(1/2)^2`
and so on

∴ Sum of the areas of all the squares

= `1^2+(1/sqrt2)^2+(1/2)^2+...`

= `1+1/2+1/4+...`

∴ a = 1, r = `1/2`

Since, |r| = `|1/2|<1`

∴ sum to infinity exists.

∴ Sum of the areas of all the squares = `1/(1-1/2)` = 2

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Chapter 2: Sequences and Series - Exercise 2.3 [Page 34]

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