Think of it this way:
You are mostly trying to find half the circumference of a circle.
Let's try the first one.
We know the diameter of the circle is 9 cm since the width of the rectangle is 9 cm.
So, find the perimeter of the rectangle.
9(2)+4(2)= 26
Now, find half the circumference of the circle. The circumference is like the perimeter of circles.
C= pi*d
You would just divide that in half.
C= pi*9/2
C= 14 I rounded it down to 14 since it was at 14.137......
14+26= 40
The perimeter of the shape is around 40.
I'm going to try one more because I think you'll get the hang out it.
Find the perimeter of the rectangle, the circumference of the circle opening, divide that by two, and subtract that from the perimeter of the rectangle.
12(2)+ 8(2)= 40
Now find the circumference.
C= pi*d/2
C= pi*8/2
C= 12.56.... round that up to 13.
40-13= 27
All you need to do for the last one is find the perimeter of the square, 12(4), then find the circumference of 2 circles with a diameter equal to 12, (since there are 4 half circles) and then add the rounded result together.
I hope this helps! Sorry, it took me awhile.
~kaikers
