In how many different ways can 8 books be arranged on a bookshelf?

Step-by-step explanation:

The answer to this question is "8 factorial."

"8 factorial" is written symbolically as 8!  

It's equal to 8·7·6·5·4·3·2·1, which  in turn is equal to:

                     56·30·24, or  40320.

The books could be arranged in 40320 different ways.

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step-by-step explanation:

the arc length is found by finding the circumference of the full circle (2xpixradius) and then dividing by 4 to find just one quarter of the circle (90 degrees).