This Blog exists for the collective benefit of all geometry students. While the posts are specific to Mr. Chamberlain's class, any and all "geometricians" are welcome. The more specific your question (including your own attempts to answer it) the better.
The INFORMAL definition of similar figures is same shape, proportional size (defined by a scale factor). For the FORMAL definition, see the TOP of page 249 and PLOP that into your G.B.
So, the side lengths will vary, but the angles will stay the same.
Visualize regular polyons, like equilateral triangles, squares, and regular pentagons. Squares of different sizes are ALL similar, because they can be related by a scale factor.
GEEZUS!(Ray William Johnson anybody?)I GOT THE FIRST PART OF #37! I'd rather not type it out, but its all algebra. Substitution and quadratics, mainly.
But, after wasting a sheets of paper trying to do the second part, I gave up. When I hear the solution, I will feel more stupid than when I heard the proof for the last one on the midterm.
I found the golden ratio online!! By using that example I was able to come up with a formula. I then used the quadratiq equation to simplify until i couldn't simplify anymore!
The answers are kinda ugly... but we are lovers of all numbers, so that shouldn't deter us!
We KNOW that Corr Sides of similar polygons are IN PROPORTION. That means that there is ONE AND ONLY ONE SCALE FACTOR that governs all of the possible proportions you can set up.
So, we're trying like crazy in this diagram to find a pair of sides that we can set equal that only involve one variable, cuz if we can set up a proportion with three numbers and a lone variable, we can solve and all will be WONDERFUL with the world (well, Jamie will still be around, but other things will be pretty-much ok).
At any rate... I digress.
How about x is to 15 as 10 is to (you tell me).
Once we get the ball rolling with that proportion, we will find one number after another and pretty soon we'll know x, y, and z. Easu as 1-2-3!!
If #37 was the only problem anyone had with sections 7-1 thru 7-3, I should have nothing but 50's on Friday's quiz (#37 will not be on it).
If you like, I'll go over 37a&b in class, but not to worry, you won't see a question like that on a quiz, test, or final exam (you may see it again in Alg 2 though... can't wait, huh?!).
ok my computers saying my first comment didnt post so if this a repeat srry. im having trouble with 15 on the self test. i think its 15... the one that says 5:5:6:7:8 or something like that. i dont get it whatsoever. i dont know how to start or what to do etc. other than that im good
hi, so i was doing the lesson 1 quiz online and one of the questions were:The Community Recreation Center is developing plans for a new sports facility. Community members can submit suggestions for the new facility, along with basic scale drawings of their ideas. Elena wants to include a new 15- by 30-meter basketball court in the athletic center. She is submitting a scale drawing on an 8.5- by 11-inch sheet of paper. Which scale should Elena use to create as large a drawing as possible on the paper? i was wondering how you would slove this.
The way I would do it is not strictly algebraic, but still works.
First, I'd add 5+5+5+6+7+8 which happens to be 36. Next, I'd find out the total measure of the interior angles. By (n-2)180, it is 720. 720/36 gives us a unit. From there, we multiply each of those values in the ratio (5,5,5,6,7,8), by 720/36(20) and we have a value for each angle.
That seems like the most elementary way to do it.
TL;DR make a unit for the numbers in the ration and multiply.
The Community Recreation Center is developing plans for a new sports facility. Community members can submit suggestions for the new facility, along with basic scale drawings of their ideas. Elena wants to include a new 15- by 30-meter basketball court in the athletic center. She is submitting a scale drawing on an 8.5- by 11-inch sheet of paper. Which scale should Elena use to create as large a drawing as possible on the paper?
For problem 10 on page 250 how are we supposed to figure those out? are the angles smaller to and not just the sides?
ReplyDeleteThe INFORMAL definition of similar figures is same shape, proportional size (defined by a scale factor). For the FORMAL definition, see the TOP of page 249 and PLOP that into your G.B.
ReplyDeleteSo, the side lengths will vary, but the angles will stay the same.
Visualize regular polyons, like equilateral triangles, squares, and regular pentagons. Squares of different sizes are ALL similar, because they can be related by a scale factor.
Ca-peesh??
GEEZUS!(Ray William Johnson anybody?)I GOT THE FIRST PART OF #37! I'd rather not type it out, but its all algebra. Substitution and quadratics, mainly.
ReplyDeleteBut, after wasting a sheets of paper trying to do the second part, I gave up. When I hear the solution, I will feel more stupid than when I heard the proof for the last one on the midterm.
If we all chip in a quarter per class, maybe we can get Nick a life... just in time for summer!
ReplyDeleteI dont understand problem 37b. my parents said dont ask you or else i wont get EC. I know that is not true ssssoooooo PLEASE HELP ME MR. C.
ReplyDeleteI found the golden ratio online!! By using that example I was able to come up with a formula. I then used the quadratiq equation to simplify until i couldn't simplify anymore!
ReplyDeleteI don’t get number 27 on page 251..(:
ReplyDelete#27 Good Question!!
ReplyDeleteThe answers are kinda ugly... but we are lovers of all numbers, so that shouldn't deter us!
We KNOW that Corr Sides of similar polygons are IN PROPORTION. That means that there is ONE AND ONLY ONE SCALE FACTOR that governs all of the possible proportions you can set up.
So, we're trying like crazy in this diagram to find a pair of sides that we can set equal that only involve one variable, cuz if we can set up a proportion with three numbers and a lone variable, we can solve and all will be WONDERFUL with the world (well, Jamie will still be around, but other things will be pretty-much ok).
At any rate... I digress.
How about x is to 15 as 10 is to (you tell me).
Once we get the ball rolling with that proportion, we will find one number after another and pretty soon we'll know x, y, and z. Easu as 1-2-3!!
(Why do I feel like singing?)
Mr. C.
the 27 was hard, but also i had issues with 37 b.
ReplyDeleteIf #37 was the only problem anyone had with sections 7-1 thru 7-3, I should have nothing but 50's on Friday's quiz (#37 will not be on it).
ReplyDeleteIf you like, I'll go over 37a&b in class, but not to worry, you won't see a question like that on a quiz, test, or final exam (you may see it again in Alg 2 though... can't wait, huh?!).
More on the golden ratio(not all of it pertains), but its pretty cool for nerdy types like myself.
ReplyDeletehttp://flowingdata.com/2010/05/10/dreaming-in-numbers/
ok my computers saying my first comment didnt post so if this a repeat srry. im having trouble with 15 on the self test. i think its 15... the one that says 5:5:6:7:8 or something like that. i dont get it whatsoever. i dont know how to start or what to do etc. other than that im good
ReplyDeletehi, so i was doing the lesson 1 quiz online and one of the questions were:The Community Recreation Center is developing plans for a new sports facility. Community members can submit suggestions for the new facility, along with basic scale drawings of their ideas. Elena wants to include a new 15- by 30-meter basketball court in the athletic center. She is submitting a scale drawing on an 8.5- by 11-inch sheet of paper. Which scale should Elena use to create as large a drawing as possible on the paper?
ReplyDeletei was wondering how you would slove this.
sorry, i was sick (well i still am) so i never got around to the geomtry hw, but is number 37 proof still up for extra credit?
ReplyDeletei dont understand how to find the angles in 15 on self test 1
ReplyDeletekevin
The way I would do it is not strictly algebraic, but still works.
ReplyDeleteFirst, I'd add 5+5+5+6+7+8 which happens to be 36.
Next, I'd find out the total measure of the interior angles. By (n-2)180, it is 720. 720/36 gives us a unit. From there, we multiply each of those values in the ratio (5,5,5,6,7,8), by 720/36(20) and we have a value for each angle.
That seems like the most elementary way to do it.
TL;DR make a unit for the numbers in the ration and multiply.
Well, Nick, you might not have "used" algebra, but you were thinking algebraically (shocker).
ReplyDeleteYou COULD HAVE set up an equation:
5x+5x+5x+6x+7x+8x=(n-2)180 where n=6 (hexagon)
substitute for n and simplify
36x=720
x=20
voila!! look ma... algebra rollercoaster NO HANDS!!
I had trouble with #s 17, 19, 29 and 31
ReplyDeleteon page 258... if that's the case, it's not on the quiz, so let's leave it for review in class tomorrow.
ReplyDeleteIn #17, you're just looking to set up a proportion and you have to be mindful of the different units (cm's and meters).
6cm is to 24m as x cm is to 2.2m
or 6cm is to 2400cm as x cm is to 220cm
or
6/2400=x/220
Cross Product Prop, baby!
i know this is in the wrong place but what are we supposed to do for the quest homework?
ReplyDeletehi anonymous!we have to go to the wiki and pick a court case and do a powerpoint about it.
ReplyDeletewhats the transitive property of similarity?
ReplyDeleteIf triangle A is similar to triangle B, and triangle B is similar to triangle C, triangle C is similar to triangle A.
ReplyDeleteThanks Carrot
Mr. C when shoud i meet u tommarow?
ReplyDelete6 b and c classroom?
ReplyDeleteNumber 23 and 25, I couldn't get.
ReplyDeletein 23- i couldn't get the problem as a whole
in 25- how do you fid an equation for AP and CP?
-confused charmi
The Community Recreation Center is developing plans for a new sports facility. Community members can submit suggestions for the new facility, along with basic scale drawings of their ideas. Elena wants to include a new 15- by 30-meter basketball court in the athletic center. She is submitting a scale drawing on an 8.5- by 11-inch sheet of paper. Which scale should Elena use to create as large a drawing as possible on the paper?
ReplyDelete