For number 8 a) I got v = 70 but I'll wait to see what others get.

Just incase you think I just repeated what you said:

http://img339.imageshack.us/img339/4...0zm9al6.th.jpg

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- May 9th 2007, 11:53 AMr_maths
For number 8 a) I got v = 70 but I'll wait to see what others get.

Just incase you think I just repeated what you said:

http://img339.imageshack.us/img339/4...0zm9al6.th.jpg - May 9th 2007, 11:55 AMqbkr21Re:
rmath you want to minimize C I haven't delt with British lbs. before!:D

- May 9th 2007, 12:00 PMnovadragon849
I got 70 as well by doing, cross multiplying to get 2v^2 = 9800 then I got 70

Is this what you guys did as well.

but then thats too little work for 5 marks. Don't you agree? - May 9th 2007, 12:07 PMqbkr21Re:
- May 9th 2007, 12:08 PMnovadragon849
ok then cheers, so how would you go about doing b and c and the steps for it?

- May 9th 2007, 12:09 PMr_maths
Don't you just substitute 70 into original equation.

C = £40

Quote:

but then thats too little work for 5 marks. Don't you agree?

1 Mark for stating "For minimum f"(x) = 0"

Quote:

so how would you go about doing b and c

Look here: http://www.mathhelpforum.com/math-he...entiation.html

C, look at top of this post. I hope its correct.

1 Mark for sub.

1 Mark for right answer. - May 9th 2007, 12:24 PMqbkr21RE: 8b
Re:

- May 9th 2007, 12:37 PMnovadragon849
anyone for number 9

- May 9th 2007, 01:00 PMJhevon
9)

a)

By the Law of Cosines:

(PR)^2 = (PQ)^2 + (QR)^2 - 2(PQ)(QR)cos(PQR)

=> 108 = 36 + 36 - 72cos(PQR)

=> cos(PQR) = [108 - 2(36)]/(-72) = -1/2

=> PQR = arccos(-1/2)

=> PQR = 2pi/3 radians

b)

Area of a sector is given by:

A = (1/2)r^2(theta)

where r is the radius and theta is the angle subtended by the arc in radians

=> A = (1/2)(6)^2(2pi/3) m^2

=> A = 12 pi m^2

c)

Using A = (1/2)absinC, we have:

A = (1/2)(PQ)(QR)sin(PQR)

=> A = (1/2)(6)(6)(2pi/3)

=> A = 9sqrt(3) m^2

....or you could use the half base times height formula (do you want to see how?)

d)

Area of segment = Area of sector - Area of triangle = 22.1

e)

Perimeter of PQRS = 6 + 6 + length of arc RSP

length of arc s is given by:

s = r(theta) , where r is the radius and theta is the angle in radians

=> s = 6(2pi/3) = 4pi

=> Perimeter = 12 + 4pi = 24.6 m