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primary 6 | Maths
| Measurement
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please help. thanks
Date Posted: 5 years ago
Views: 500
Gwendolyn, which part are you struggling with? Any workings that you have done?
i had done the workings. just confused as my answers differ from the correction i copied in school. need to clarify part 2
Find the perimeter for the whole circle and add 10cm to it.
If you see the diagram, it consists of 4 quarters of the perimeter of the circle. But the bottom right of it includes 10cm, derived from 30cm/3.
can you explain why i should find the perimeter of whole circle rather than the perimeter of semicircle?
It should be add 20cm instead of 10cm only. You forgot the 10cm at the left middle
Apologies yea add 20cm.
The perimeter of the semicircle pertains to only the top half of the shaded area. The bottom half has 2 quarters of a circles perimeter as well. One in the middle and one on the right.
thanks. i got what you mean, i can kinda visualise it now
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On top there are two quarter circles that can be combined together to form one semicircle.
At the bottom the quarter circle can be combined with the curved shaded area to form 1 square.
So the shaded area = 1 square + 1 semicircle.
b)
This asks you to find the perimeter.
The four curved sections are that of quarter circles. So the curved length of 4 quarter circles added together will give you the circumference of one full circle.
The two straight sections are equal to the radius of the circle.
So perimeter = 1 full circle's circumference + 2 x radius of circle