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anonymous
 one year ago
a can of beans has surface area 359 cm^2. Its height is 10 cm. What is the radius of the circular top?
anonymous
 one year ago
a can of beans has surface area 359 cm^2. Its height is 10 cm. What is the radius of the circular top?

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anonymous
 one year ago
Best ResponseYou've already chosen the best response.0Do you know the formula for calculating the surface area of a sphere?

anonymous
 one year ago
Best ResponseYou've already chosen the best response.0Pir^2 is just the surface area of one lid, so for the 2 lids it would be 2Pir^2 what is the formula for the walls?

anonymous
 one year ago
Best ResponseYou've already chosen the best response.0im following the steps the teacher gave me for notes but i keep getting them wrong. This is the 5th problem like this I've attempted to do.

anonymous
 one year ago
Best ResponseYou've already chosen the best response.0The wall of the can would be circumference x height. (The height is given). What is the circumference?

anonymous
 one year ago
Best ResponseYou've already chosen the best response.0I did not calculate the answer. I'm doing step by step with you.

anonymous
 one year ago
Best ResponseYou've already chosen the best response.0I apologize, you wrote the correct answer earlier. The surface area of the wall is 2 pirh.

anonymous
 one year ago
Best ResponseYou've already chosen the best response.0And what you wrote the very first time "2pir^2+2pirh" is also correct.

anonymous
 one year ago
Best ResponseYou've already chosen the best response.0So far looks good. It may be easier to factor out a 2 and write it as 359 = 2 (pir^2 + 10pir). You're on the right track.

anonymous
 one year ago
Best ResponseYou've already chosen the best response.0in my notes my teacher has me equal it out to 0 following this it would be 0 = 2pir^2+20pir359

phi
 one year ago
Best ResponseYou've already chosen the best response.1this one is more painful than that. How about divide all term by 2pi and write it as \[ r^2 + 10 r  \frac{359}{2 \pi} = 0 \] if we use a calculator, that is about \[ r^2 + 10 r  57.1366=0 \] to find r we could use the quadratic formula

anonymous
 one year ago
Best ResponseYou've already chosen the best response.0after that step i'm getting very confused

anonymous
 one year ago
Best ResponseYou've already chosen the best response.0Give me a few minutes. I'll try it the way you have it in your notes.

anonymous
 one year ago
Best ResponseYou've already chosen the best response.0x=b+ sqr rt, b^24ac / 2a

phi
 one year ago
Best ResponseYou've already chosen the best response.1yes, quadratic formula. if you first divide by 2pi most of the numbers get a bit smaller and you would have a=1, b=10 , c= 57.1366

anonymous
 one year ago
Best ResponseYou've already chosen the best response.010pi+ sq rt. 1004(!)(57.1366)/2?

phi
 one year ago
Best ResponseYou've already chosen the best response.1if you are doing \[r^2 + 10 r  57.1366=0 \] b is 10 (not 10pi) a=1 so 4ac is just 4*57.1366 (notice c is negative)

phi
 one year ago
Best ResponseYou've already chosen the best response.1so \[ \frac{10+ \sqrt{100 + 228.5465}}{2} \]

phi
 one year ago
Best ResponseYou've already chosen the best response.1I would pick the + sqrt because otherwise we get a negative radius

anonymous
 one year ago
Best ResponseYou've already chosen the best response.0am i calculating this right

anonymous
 one year ago
Best ResponseYou've already chosen the best response.0what am i doing wronnggggg

phi
 one year ago
Best ResponseYou've already chosen the best response.1can you get this far: \[ \frac{10+ \sqrt{100 + 228.5465}}{2}\] (by the way for c = 359/(2pi) I would use all the digits the calculator has)

phi
 one year ago
Best ResponseYou've already chosen the best response.1for \[ r^2 + 10 r  57.1366=0 \] a=1, b=10, c= 57.1366 (roughly) let's first figure out b^2 4 * a *c that is 100  4 * 1 * 57.1366 what does that simplify to ?

anonymous
 one year ago
Best ResponseYou've already chosen the best response.0i'm getting 118.5465.

phi
 one year ago
Best ResponseYou've already chosen the best response.14*57.1366= 228.5465 now do 100  (228.5465)

anonymous
 one year ago
Best ResponseYou've already chosen the best response.0I made a mistake in my calculation. I don't want to post until I figure out where the error is.

phi
 one year ago
Best ResponseYou've already chosen the best response.1notice it is minus a minus. that makes it a +

anonymous
 one year ago
Best ResponseYou've already chosen the best response.0i forgot the other minus

phi
 one year ago
Best ResponseYou've already chosen the best response.1yes. so make a note: Be careful about the minus signs (they are evil) now find the square root.

phi
 one year ago
Best ResponseYou've already chosen the best response.1yes, that looks good. do they want the answer rounded ?

anonymous
 one year ago
Best ResponseYou've already chosen the best response.0so i was right earlier. Thank you both so much for your help!

anonymous
 one year ago
Best ResponseYou've already chosen the best response.0Sorry I wasn't able to help you through it

phi
 one year ago
Best ResponseYou've already chosen the best response.1if we use 4.06 in the original formula we get 358.67 or about 359, so it checks out.

anonymous
 one year ago
Best ResponseYou've already chosen the best response.0If it helps I'll post how to do it in a calculator that has fractions

anonymous
 one year ago
Best ResponseYou've already chosen the best response.0\[\frac{ 20 + \sqrt{20^2+ 8(\frac{ 359 }{ \pi })} }{ 4 }\]

anonymous
 one year ago
Best ResponseYou've already chosen the best response.0If your calculator allows you to enter the above equation (in one step) you'll get the same answer. I put in + 8 since the two negatives become positive.
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