math ? has me stumped

[poohbear]

I have a math question that has me stumped..please help
here is the information needed to answer the question:
A square, S1, with sides of 10cm. A second square, S2, with sides of 5(square root of 2) cm is inscribed in S1. Athird square, S3, is inscribed in S2 so that the vertices of S3 lie at the midpoints of the sides of S2. This process is continued indefinitely.

Here is the question.... If the process of drawing squares were to continue indefinitely, then what would be the sum of the infinite geometric series of the squares perimeter values, correct to the nearest hundreth of a centimetre?

Please help me and explain how to do this type of question..I need to understand it..Thanks :?

 

[stapel]

You are given that the first square's sides are of length 10, the next of length 5sqrt(2), and that the sides' lengths form a geometric sequence.

What is the common ratio "r"?

What is the formula for the sum of an infinite geometric sequence?

What value do you get when you plug in "10" for "a" and the common ratio value for "r"?

Eliz.

 

[poohbear]

The common ratio is 1/2 or .5

what i don't know is the equation. I have all the other information. but am confused as to what the formula is for it.

 

[Denis]

too tired to do a http://www.google.com search?

here's a site you'd get:
http://www.richland.edu/james/lecture/m ... etric.html

 

[stapel]

The common ratio is 1/2 or .5

How are you getting that r = 0.5? You have (5sqrt(2))/(10) = sqrt(2)/2, which does not equal 0.5...?

As for the formula, it should be in a box or some other "call-out" in your text, on the section on geometric series in the chapter on sequences and series. Check the index in the back of the book, if you've misplaced the info.

Eliz.