 Likes:  1

1. ## Helping With Homework

When I was down in Kingston yesterday my 12 year old niece was all set with some math questions for me. She's in an enrichment class.
Here they are:
• Given a Trapezoid with certain specified dimensions for major side, minor side and height, what are the dimensions of a similar Trapezoid of 1/10th the area?
• Given a hexagon with specified length of segment, what is the dimension of the same segment on a hexagon of 1/10 the area?

Well I did them both initially by using a spreadsheet where she could pick a number and refine her guess as she got close to the required area.
Later on I worked out the algebra which is easy enough for the hexagon but requires some nasty 10th grade math for the trapezoid. Pretty challenging stuff for Grade 7 if you ask me.  Reply With Quote

2. The answer is D all of the above   Reply With Quote

3. Originally Posted by gnuyork The answer is D all of the above Incorrect, the answer is Pi, if it happens not to be the answer the teacher is seeking at least you can eat it later...

Reminds me, pecan pi(e) from Thanksgiving is calling my name.  Reply With Quote

4. Do you have Common Core up in Canada?

I'm not sure what the controversy is, or if I have grasped the problem (if it is one), but I have seen some examples, and I must admit to being somewhat perplexed as to the logic in this form of pedagogy.

I kinda get the intention, but I kinda don't.  Reply With Quote

5. Very interesting, Ray. My geometry and algebra skills are rusty; maybe I need to re-do the maths that 7th graders are expected to know:

John  Reply With Quote

6. As for the trapzoid, as the ratio's stay the same, isn't it just making both sides and height a factor sqrt(10) smaller?
Old area: 1/2(a+b)xh=A
New area: 1/2((a/sqrt(10)+b(/sqrt(10))x(h/sqrt(10))=1/sqrt(10) x 1/2(a+b) x 1/sqrt(10) x h = 1/10 x 1/2(a+b)xh  Reply With Quote

7. Originally Posted by Martin As for the trapzoid, as the ratio's stay the same, isn't it just making both sides and height a factor sqrt(10) smaller?
Old area: 1/2(a+b)xh=A
New area: 1/2((a/sqrt(10)+b(/sqrt(10))x(h/sqrt(10))=1/sqrt(10) x 1/2(a+b) x 1/sqrt(10) x h = 1/10 x 1/2(a+b)xh
In other words, kinda smallish, yeah?   Reply With Quote

8. Originally Posted by Chronopolitano In other words, kinda smallish, yeah? Well, that depends on the size of your trapezium   Reply With Quote

9. Originally Posted by Martin As for the trapzoid, as the ratio's stay the same, isn't it just making both sides and height a factor sqrt(10) smaller?
Old area: 1/2(a+b)xh=A
New area: 1/2((a/sqrt(10)+b(/sqrt(10))x(h/sqrt(10))=1/sqrt(10) x 1/2(a+b) x 1/sqrt(10) x h = 1/10 x 1/2(a+b)xh
Basically yes that is how the algebra worked out. You have a better spatial concept than I do.   Reply With Quote

#### Posting Permissions

• You may not post new threads
• You may not post replies
• You may not post attachments
• You may not edit your posts
•