Is this the right answer? Math problem.

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thread starter person Feb 21 2010 + PM | QUOTE | PERMALINK | REPORT

A certain windshield wiper is 10 inches long. The rubber wiping blade is 6 inches long and attached at the outside end ( opposite the center of rotation).If the wiper sweeps through a 150 degree angle, how much area is covered by the blade? State the answer in terms of pi. So I subtracted 6 from 10 because the rubber wiping blade is the one sweeping. 10-6=4 C= 4squared(3.14) C= 16(3.14) C= 50.24 150/360 degrees = 0.4 C= 0.4(50.24) C= 20.1in squared Not very good with math so idk if it's right XD

My Characters: postalco - 52 Bera Gunslinger

xTurtally + PM | QUOTE | PERMALINK | REPORT

Edit: Disregard this. I can't read. Yeah 35(pi). :/ 10^2(pi) x 5/12 - 4^2(pi) x 5/12 500(pi)/12 - 80(pi)/12 420(pi)/12 35(pi)

My Characters: jed3864 - 124 Bera I/L Arch Mage

4thDegreeBaka + PM | QUOTE | PERMALINK | REPORT

ok what you do, find the area of the whole windsheild first by normal then multpliy by 150/360 then, subtract the area thats not with the rubber blade (16pi) from taht amount edit: i got 35pi edit2: i mean 35(pi) inches^2

My Characters: 4DegreeBaka - 56 Yellonde Aran in Memory

cdcase 02/21/10 + PM | QUOTE | PERMALINK | REPORT

[quote] xTurtally : I got 42(pi). What I did was find the area of the whole wiper (the big half circle) minus the area that doesn't get wiped (the inner half circle). [/quote] it's not 1 half of a circle it's 5/12 of a circle.

My Characters: uoYoTpaFI - 85 Broa Wind Archer

person 02/21/10 + PM | QUOTE | PERMALINK | REPORT

[quote] xTurtally : I got 42(pi). What I did was find the area of the whole wiper (the big half circle) minus the area that doesn't get wiped (the inner half circle). The question says "state in terms of pi", so never turn it into 3.14 and multiply. Just leave pi on its own like it's a variable. [/quote] So I have to use pi in my answer? because I thought it meant that I had to show my work using pi O.o

My Characters: postalco - 52 Bera Gunslinger

xTurtally + PM | QUOTE | PERMALINK | REPORT

[quote] cdcase : it's not 1 half of a circle it's 5/12 of a circle. [/quote] Blargh, right. Sorry. @above: Yeah.

My Characters: jed3864 - 124 Bera I/L Arch Mage

4thDegreeBaka 02/21/10 + PM | QUOTE | PERMALINK | REPORT

[quote] xTurtally : Wait what? What am I missing here. ): [/quote] 150/360 is not 180/360... lol

My Characters: 4DegreeBaka - 56 Yellonde Aran in Memory

shadow1049 02/21/10 + PM | QUOTE | PERMALINK | REPORT

Cookie?

My Characters: Neko6 - 54 Bera Spearman

4thDegreeBaka + PM | QUOTE | PERMALINK | REPORT

ok just to clarify: the answer i got is 35(pi) inches^2 Work: area of whole windshield wiper coverage: 150/360(10)^2(pi) do the math and you get 41 2/3(pi) inches^2 area without the rubber blade coverage: 150/360(4)^2(pi) do the math and you get 6 2/3(pi) inches^2 subtract 6 2/3(pi) inches^2 from 41 2/3(pi) inches^2 and you get 35(pi) inches^2 hope i helped

My Characters: 4DegreeBaka - 56 Yellonde Aran in Memory

BeSubtle 02/21/10 + PM | QUOTE | PERMALINK | REPORT

Use the 'sector area' formula : (theta/360)(pi)r� = (150/360)(pi)(10^2) (try to keep pi in your answer, sorry, i'd show you how to do it irl xD )

My Characters: BeSubtle - 61 Windia Hunter

person 02/21/10 + PM | QUOTE | PERMALINK | REPORT

[quote] 4thDegreeBaka : ok what you do, find the area of the whole windsheild first by normal then multpliy by 150/360 then, subtract the area thats not with the rubber blade (16pi) from taht amount edit: i got 35pi edit2: i mean 35(pi) inches^2 [/quote] Do you mean the windshield or the windshield wiper?

My Characters: postalco - 52 Bera Gunslinger

YaItsKynic + PM | QUOTE | PERMALINK | REPORT

You have two circles, one with a 10 inch radius (full length) and one with a 4 inch radius (full length - length of blade). First, you have to find the difference between the two. Area of circle with 10 inch radius: A = 10*10*pi = 100pi Area of circle with 4 inch radius: A = 4*4*pi = 16pi Area of full circle, circular ring: 100pi - 16 pi = 84pi *Revised because I guess it caused the TS confusion? 84pi is the area if the windshield wiper went in a full circle. However you said it only goes 150 degrees, so you multiply 84pi by [150/360] 84pi * [150/360] = 35pi

My Characters: United2 - 160 Windia Night Lord

Myterac + PM | QUOTE | PERMALINK | REPORT

Yes, the answer is 35pi EDIT: Don't let the guy above me confuse you. He is also correct but he multiplied pi out. The answer is 35pi if you leave it in terms of pi Or it is 3.14 x 35 which 109.9 if you multiply it out

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person 02/21/10 + PM | QUOTE | PERMALINK | REPORT

I got confused after he found the difference.

My Characters: postalco - 52 Bera Gunslinger

4thDegreeBaka 02/21/10 + PM | QUOTE | PERMALINK | REPORT

[quote] person : I got confused after he found the difference. [/quote] what he did was find the area of the circle if it was 360 degrees first, then multiplied to make it so it was 150 degrees what i did was find each area at 150 degrees then subtract them

My Characters: 4DegreeBaka - 56 Yellonde Aran in Memory