
By: parent603 (offline) Sunday, July 01 2012 @ 10:53 PM CDT (Read 3182 times)



parent603 
Please help to answer Henry Park Preliminary 2011 Paper 2 Q10.
Thanks for your help!

Newbie
Registered: 11/07/11 Posts: 14





By: jo sarah (offline) Wednesday, July 04 2012 @ 08:55 AM CDT



jo sarah 
Hi,
Label the square starting from top left corner clockwise as ABCD, and centre of square is centre of circle P.
Area of a leaf between points A and P = area of semicircle radius 6 cm  area of square base 12 cm and height 6 cm
= 0.5 x (pi) x 6 cm x 6 cm  0.5 x 12 cm x 6 cm
= 20.5486 cm^2
therefore,
Area of shaded region = area of triangle ABC  area of leaf
= 0.5 x 12 cm x 12 cm  20.5486 cm^2
= 51.4513 cm^2
= 51.45 cm^2 (to 2 d.p.)
Hope this helps.
jo sarah

Regular Member
Registered: 03/20/12 Posts: 111





By: jo sarah (offline) Wednesday, July 04 2012 @ 08:56 AM CDT



jo sarah 
Hi,
Label the square starting from top left corner clockwise as ABCD, and centre of square is centre of circle P.
Area of a leaf between points A and P = area of semicircle radius 6 cm  area of square base 12 cm and height 6 cm
= 0.5 x (pi) x 6 cm x 6 cm  0.5 x 12 cm x 6 cm
= 20.5486 cm^2
therefore,
Area of shaded region = area of triangle ABC  area of leaf
= 0.5 x 12 cm x 12 cm  20.5486 cm^2
= 51.4513 cm^2
= 51.45 cm^2 (to 2 d.p.)
Hope this helps.
jo sarah

Regular Member
Registered: 03/20/12 Posts: 111





By: jo sarah (offline) Wednesday, July 04 2012 @ 08:59 AM CDT



jo sarah 
Hi,
Let's label the square starting from top left corner clockwise as ABCD, and centre of square is centre of circle P.
Area of a leaf between points A and P = area of semicircle radius 6 cm  area of square base 12 cm and height 6 cm
= 0.5 x (pi) x 6 cm x 6 cm  0.5 x 12 cm x 6 cm
= 20.5486 cm^2
therefore,
Area of shaded region = area of triangle ABC  area of leaf
= 0.5 x 12 cm x 12 cm  20.5486 cm^2
= 51.4513 cm^2
= 51.45 cm^2 (to 2 d.p.)
Hope this helps.
jo sarah
PS: is isn't clear if there is to be a small portion to be added on the left of the figure. In my solution, i have treated it as not to be there and ignored it.

Regular Member
Registered: 03/20/12 Posts: 111





By: Jane Lim (offline) Tuesday, July 10 2012 @ 12:34 AM CDT



Jane Lim 
Hi,
The given answer is 43.73 square cm but your answer is 51.45 square cm.
Please confirm.
Thank you.

Newbie
Registered: 10/01/10 Posts: 11





By: jo sarah (offline) Tuesday, July 10 2012 @ 09:27 AM CDT



jo sarah 
hi,
someone has pointed out that i seem to have missed even a small portion (on the left), and that could mean that the answer might even be larger than mine.
It is a little uncertain if the "little portion" on the left of the figure is included in the original question (for we know that many of these papers are cleaned out copies.
Please also note that we might not necessarily go by the socalled given answers all the time because i have encountered many an incorrect answer before though i am not sure about this one yet.
many thanks.

Regular Member
Registered: 03/20/12 Posts: 111





By: echeewh (offline) Monday, July 16 2012 @ 01:38 AM CDT



echeewh 
Dear All,
I have already done some research on the question itself, esp on the diagram. And came up with a 'reengineered' one of what I believe could be the actual one. Appreciate that you take a look at that in a new post created by me entitled "Henry Park Prelim 2011 Paper2 Qn 10  Updates".
Cheers,
Edward

Active Member
Registered: 04/21/11 Posts: 627



