Ahhh!!!! Algebra!!
Moderators: Section Moderators, Forum Moderators
-
- Posts: 10
- Joined: Sun May 13, 2012 2:18 pm
Ahhh!!!! Algebra!!
Hi,
My dd can't grasp alegbra and consequently is finding it hard to explain this=Area=1/2(a+b)H for the area of a trapezium.Could I please have a clear explanation....Thanks
My dd can't grasp alegbra and consequently is finding it hard to explain this=Area=1/2(a+b)H for the area of a trapezium.Could I please have a clear explanation....Thanks
Re: AHHH!!!!ALGEBRA!!
i think uve to post this in maths forum isnt it. is that from VR? coz i havent come across such a qstn in VR.
Re: AHHH!!!!ALGEBRA!!
This isn't algebra, it's area!
To find the area of a trapezium you find the average length of the parallel sides and then multiply by the perpendicular distance between them.
To find the area of a trapezium you find the average length of the parallel sides and then multiply by the perpendicular distance between them.
Re: AHHH!!!!ALGEBRA!!
Guest55 wrote:This isn't algebra, it's area!
To find the area of a trapezium you find the average length of the parallel sides and then multiply by the perpendicular distance between them.
is this from VR?
-
- Posts: 204
- Joined: Wed Jan 25, 2012 8:43 pm
Re: AHHH!!!!ALGEBRA!!
It is Geometry, not algebra
Formula given by both suttoncoldfield and Guest55 is of course correct.
Here is a derivation of the formula for trapezium's area.
Let us say we have a trapezium with two parallel sides (of lengths 'a' and 'b'), and a height of 'H'.
Draw a diagonal across the trapezium i.e. draw a line connecting two opposite vertices. Now, the trapezium looks like a combination of Two Triangles whose base lines are parallel to each other. These triangles have base lengths of 'a' and 'b', and both have the the same height of 'H'.
Area of Trapezium is therefore = Sum of Areas of the Two Triangles
= (aH)/2 + (bH)/2
= (a+b)H / 2
Derivation of Triangle's Area ( 1/2 x base x height) is of course a different story
Btw, I just noted this in wikipedia
Formula given by both suttoncoldfield and Guest55 is of course correct.
Here is a derivation of the formula for trapezium's area.
Let us say we have a trapezium with two parallel sides (of lengths 'a' and 'b'), and a height of 'H'.
Draw a diagonal across the trapezium i.e. draw a line connecting two opposite vertices. Now, the trapezium looks like a combination of Two Triangles whose base lines are parallel to each other. These triangles have base lengths of 'a' and 'b', and both have the the same height of 'H'.
Area of Trapezium is therefore = Sum of Areas of the Two Triangles
= (aH)/2 + (bH)/2
= (a+b)H / 2
Derivation of Triangle's Area ( 1/2 x base x height) is of course a different story
Btw, I just noted this in wikipedia
Didn't know that a trapezium does not have parallel sides if it is on the other side of the pond. One learns something everydayWikipedia wrote: The word trapezium has several meanings:
(Outside the US) – a quadrilateral with one pair of parallel sides (a shape known in the US as a trapezoid).
(In the US) – a quadrilateral with no parallel sides (a shape known elsewhere as a general irregular quadrilateral).
-
- Posts: 102
- Joined: Sat Dec 17, 2011 1:02 pm
Re: AHHH!!!!ALGEBRA!!
Is this a question for eleven plus maths?
Last edited by BusyQueenBee on Mon Jul 09, 2012 10:00 pm, edited 1 time in total.
Re: AHHH!!!!ALGEBRA!!
I don't know about other areas and without digging out the paper I cannot remember whether the Essex CSSE Maths this time required such knowledge, but the formula is one of the two "you might need to use these" given at the beginning of the SATS Level 4-6 Maths papers.
Outside of a dog, a book is a man's best friend. Inside of a dog it's too dark to read.Groucho Marx
Re: AHHH!!!!ALGEBRA!!
They are KS3 papers ... not appropriate for KS2 children as they are based on the KS3 'old' curriculum. They would not be used in KS3 now as they are not focused on the new style of questioning.
Re: Ahhh!!!! Algebra!!
suttoncoldfield wrote:Hi,
My dd can't grasp alegbra and consequently is finding it hard to explain this=Area=1/2(a+b)H for the area of a trapezium.Could I please have a clear explanation....Thanks
Hi Not to worry mate and it is absolutely great to see dd has been challenged. Just think of 'area' as the space inside the shape and "Area=1/2(a+b)H" will make more sense if you draw a trapezium and label the two parallel length as "a and b" of your choice. All then is required to substitute the appropriate values and obtain a numerical answer.
However, if your dd is struggling with substitution then that's algebra and I would suggest dd should work on that before moving on to Areas which off-course can be done with using letters and just simply do the steps but I think using "Area=1/2(a+b)H" serves a great purpose in enhancing algebraic skills.
Any questions, please do not hesitate to contact.
Regards
AEC