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Ledah
Group Title
Two regular decagons have areas of 30 mm² and x² + 7x mm². What values of x make the decagons congruent?
 2 years ago
 2 years ago
Ledah Group Title
Two regular decagons have areas of 30 mm² and x² + 7x mm². What values of x make the decagons congruent?
 2 years ago
 2 years ago

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apoorvk Group TitleBest ResponseYou've already chosen the best response.1
Since the areas are equal, equate the expressions for both areas: \[30 = x^2 + 7x\] Now, bring every term to the same side, and lo! you have a quadratic. solve it, find 'x' and enjoy!
 2 years ago

FoolAroundMath Group TitleBest ResponseYou've already chosen the best response.1
Two polygons are congruent if they are exactly the same. What can you say about the area of two congruent polygons?
 2 years ago

Ledah Group TitleBest ResponseYou've already chosen the best response.0
They should also be the same
 2 years ago

FoolAroundMath Group TitleBest ResponseYou've already chosen the best response.1
So, all you have to do is equate their areas and get a quadratic equation as obtained by @apoorvk and solve it.
 2 years ago

Ledah Group TitleBest ResponseYou've already chosen the best response.0
I got 5 and 6 as an answer.. I'm not sure if its right I'm still checking my work
 2 years ago

apoorvk Group TitleBest ResponseYou've already chosen the best response.1
Umm, sorry that isn't correct  did you split the middle term and factorize it?
 2 years ago

FoolAroundMath Group TitleBest ResponseYou've already chosen the best response.1
\(x=5\) does not satisfy the equation. What you have is \(x^{2}+7x30 = 0\) Can you factorise the left hand side?
 2 years ago
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