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-   -   help (the area of a sector) (http://mymathforum.com/algebra/38114-help-area-sector.html)

J.Xavier September 13th, 2013 06:02 AM

help (the area of a sector)
 
I'm using Basic Mathematics by Serge Lang & I'm currently on the geometry section of the book. He explained angles & their measurements in degrees, then on how to get the area of the sector formed by two rays.

area of S = x/360 multiplied by the area of the disc

One of the exercises goes like this. It gives you a 60 degree angle and the area of the disc, which is 60 in^2

So I look for the ratio between the angle and the full circle

60/360 = 1/6

then I multiply that by the area of the disc 60 in^2

= 10 in^2

but the book says the answer is 1

Am I doing anything wrong or is it the book?

MarkFL September 13th, 2013 06:42 AM

Re: help (the area of a sector)
 
The book has made an error.

skipjack September 13th, 2013 11:33 AM

It's likely that the book should have given 6 in as the area of the disc instead of 60 in. A reviewer on Amazon specifically notes that there are many discrepancies between the questions and the answers in this book. However, most other aspects of the book are favourably reviewed.


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