The figure shows the top side of a circular medallion made

[Guest]

Please refer to the attached problem.

I think I know how to start the problem, but not sure how to reach an answer that fits the answers provided by the exam.

Answer = Area of Circular Medallion - Area of Circular Colored Glass = Area of Metal Frame

pie*r^2 - pie *(r - s)^2

= pie * r^2 - pie * r^2 - 2s + s^2

Is that correct so far? And how do I reach a final answer?

Thank you!

[Guest]

[givemeanid]

YOu are on the right track. You just need to factorize a little more.

pi*r^2 - pi*(r - s)^2
= pi * r^2 - pi * (r^2 - 2rs + s^2)
= pi*r^2 - pi*r^2 + 2pi*r*s - pi*s^2
= 2pi*r*s - pi*s^2
= pi*s(2r - s)
= E

[Guest]

so close....clear explanation.

Thanks givemeanid.

[StaceyKoprince]

Nice job once again, givemeanid. You've been a great help on the forums - keep up the good work!

[avlanib]

What made you realize that "r" is the radius of the complete circle, encompassing the non shaded region and the shaded region? I thought r was radius of the the non shaded circle and s is the width of the frame(width of the shaded frame). So (r+s) was the complete circle radius and pi.r^2 is the radius of the inner circle.????

Please tell me this question is from the 700-800 difficutly level :)

Thank you for your help in advance.

[vimalshahmph]

in the question it clearly says that

figure is a top view of medallion made of circular glass surrounded by the frame.

the next line says radius of the medallion is r.........

if you take a good hard look...... you will figure it out......haste is waste while reading the problem.......

this would be a 600 level problem..........

[RonPurewal]

in the question it clearly says that

figure is a top view of medallion made of circular glass surrounded by the frame.

the next line says radius of the medallion is r.........

if you take a good hard look...... you will figure it out......haste is waste while reading the problem.......

this would be a 600 level problem..........

remember, guys, there's little point in estimating the difficulty level of problems. even if you could somehow ascertain the precise difficulty level (which of course you can't), that's not the point.

the only "difficulty level" that matters - for a student studying for the exam - is "too easy for me / just right / too hard for me".
the only people who should care about numerical difficulty levels are people who write exams.

the point of studying these sorts of problems is to learn takeaways that you can take into other problems, a goal that is completely independent of the official difficulty level of the problem.