Alan

pi doesn't have an area - it's just a number.  If you want the area of a circle it is pi*r²  where r is the radius.

1.2/3 = 3.6/9 = 0.4

Not infinity, just a large number.  See http://www.wolframalpha.com/input/?i=2%5E2011

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Time taken = distance/speed, so time saved here = 8/16 - 8/18 hours or (8/16 - 8/18)*60 minutes (≈3.3 minutes)

x² - 9x + 10 can be factored as (x - 1)*(x + 10) so the side lengths will be x-1 (= 12 in²) and x+10 (=23in²)

The height of an equilateral triangle is sqrt(3)/2 times the side length.

The area is given by half base times height so Area = (1/2)*8*(8*sqrt(3)/2) = 16*sqrt(3)

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x² + 7x - 8 → (x - 1)(x + 8)

As written there is nothing to solve!  What do you want to do - find the value of t that makes r(t) = 0, or what?

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Do it as follows:

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sin^5/2(x) → sin^1/2(x)*sin^2(x)  so:

sin^1/2(x)(cos(x))-sin^5/2(x)(cos(x))  →  sin^1/2(x)*cos(x)*(1 - sin^2(x)) → sin^1/2(x)*cos(x)*cos^2(x) → sin^1/2(x)*cos^3(x)

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