Tutor MathsGuru: Ask me for your burning Maths questions!

[PiggyLalala]

Brenda10:

amirtha:

Dear Maths Guru


Could you pls help to solve the below P6 question.


http://i56.tinypic.com/33m0nm1.jpg\">


thks

Hi, extracted answer from dd working:


4 x 4 = 16
16 /2 = 8
1/2 x 2 x 4 = 4
8 + 4 = 12
1/2 x 12 x 12 = 72
72 -12 = 60

Answer: 60cm2

Hi Brend10,
just curious, did the teacher go through this question in class? If yes, what is the method? I think it is not very clear that the height of triangle AFE is 4cm. TIA

[Brenda10]

PiggyLalala:

Brenda10:

[quote=\"amirtha\"]Dear Maths Guru


Could you pls help to solve the below P6 question.


http://i56.tinypic.com/33m0nm1.jpg\">


thks

Hi, extracted answer from dd working:


4 x 4 = 16
16 /2 = 8
1/2 x 2 x 4 = 4
8 + 4 = 12
1/2 x 12 x 12 = 72
72 -12 = 60

Answer: 60cm2

Hi Brend10,
just curious, did the teacher go through this question in class? If yes, what is the method? I think it is not very clear that the height of triangle AFE is 4cm. TIA[/quote]Hi PiggyLalala

No. This is what she had done at home during the holiday.

She visualize the drawing and come with this this area is a small square with size of 4cm.

We did not check as her answer was match with the answer key that provided.

[amirtha]

[quote]Hi PiggyLalala


No. This is what she had done at home during the holiday.

She visualize the drawing and come with this this area is a small square with size of 4cm.

We did not check as her answer was match with the answer key that provided.[/quote]
Hi Brenda10

Thanks for your working. The answer \"60\" is correct as per the answer key.

[MathIzzzFun]

MathIzzzFun:

amirtha:

Dear Maths Guru


Could you pls help to solve the below P6 question.


http://i56.tinypic.com/33m0nm1.jpg\">


thks

Hi

A jigsaw puzzle approach :lol:

http://i55.tinypic.com/4t6fs3.jpg\">

cheers.

Hi

The worked solution

http://i54.tinypic.com/29dern8.jpg\">

cheers.

[PiggyLalala]

MathIzzzFun:

MathIzzzFun:

Hi

The worked solution

http://i54.tinypic.com/29dern8.jpg\">

cheers.

Nice Solution but again how do we explain that the height of triangle Y and Z to be the same.

[MathIzzzFun]

PiggyLalala:

MathIzzzFun:

[quote=\"MathIzzzFun\"]

Hi

The worked solution

http://i54.tinypic.com/29dern8.jpg\">

cheers.

Nice Solution but again how do we explain that the height of triangle Y and Z to be the same.[/quote]Hi

copy triangle ADG and paste it over triangle ABE, and you will see that Y and Z overlaps and are the same - ADG and ABE are reflections in the axis AC.

cheers.

[Dharma]

PiggyLalala:

Dharma:

http://i55.tinypic.com/24enbcw.gif\">

Thanks for the solution.
But how do we explain to the kids that
GE = 1u
GF = HF = 2u since the ratio of AE:AB = 1:2
(By similar triangles????)

Also, do we need to bring in HF???
TIA

We assume that GE = 1u
Triangles GFE and ABE is similar triangles. So AB : AE = GF : GE = 2 : 1
Since AE is the midpoint of AD, we know that AE = ½ X 12 = 6cm.
AGFH is a square. If GE is 1u, then GF is double of GE (i.e. 2u)
GE = HF = 2u
AE = AG + GE = 2u + 1u = 3u (AG = HF)
3u = 6cm
1u = 2cm

[tianzhu]

Brenda10:

She visualize the drawing and come with this this area is a small square with size of 4cm.

Hi Brenda10.

This question has been discussed previously in the PSLE Maths thread.

Best wishes

http://farm5.static.flickr.com/4105/5037820184_49243da940_z.jpg\">

http://farm5.static.flickr.com/4103/5037820252_8aa41e056c_z.jpg\">

[Augmum]

Brenda10:

ChiefKiasu:

[quote=\"Brenda10\"]
Hi, extracted answer from dd working:
4 x 4 = 16
16 /2 = 8
1/2 x 2 x 4 = 4
8 + 4 = 12
1/2 x 12 x 12 = 72
72 -12 = 60

Answer: 60cm2

Can your DD explain why she assumes that the height of triangle AFE to be 4cm?

Hi Chief
DD said she visualize the small area as a square.
Now she is worry and want to :siam:[/quote]hi brenda

Triangle AEF + triangle AFB = triangle AEB

Triangle AEB = ½ x 6 x 12 = 36
Triangle AEF = ½ x 6 x h (h = height of triangle AEF)
\t\t= 3 h
Triangle AFB = ½ x 12 x h
\t\t= 6 h
( same h as AFC is a straight line and also diagonal for sq ABCD)

3h +6 h = 36
9 h = 36
\t h = 4
The height of the triangle AEF is 4 cm

amirtha:

Dear Maths Guru
Could you pls help to solve the below P6 question.
http://i56.tinypic.com/33m0nm1.jpg\">
thks

[PiggyLalala]

:thankyou: for all the various approaches to find the area of shaded region.

:lovesite: There is just so much to learn in here.