Question

Area and Circumference of a Circle

Answer 1

\[A = \pi r ^{2}\]
\[C = 2\pi r\]
Will this help or do you also need help with solving the problems? (If so, all four or are there any specific ones you are having trouble with?)

Answer 2

all because i need to know how to solve this

Answer 3

I just found out I have to go :( but hopefully someone else can help you out! Sorry...

Answer 4

I'm back!
The first question deals with area. The cost to paint the sign is c=3.5A, where A is the area and c is the cost. I likte to put the problems in equations early on so I can understand what I'm dealing with.
Knowing that A = pir^2, we need to find the radius. The diameter is already given, and we know that r = .5d.

The second question is actually a lot easier than it looks. Congruent means that they are the same size. Since the diameters are the same length, we know that the circles are the same size. The curve ABC is simply the sum of half of the circumference of the first circle and half of the circumference of the second circle. Since the circles are the same size, ABC is equal to the total circumference of one of the circles. You can use C = 2pi*r for this problem.

3. The Area of the shaded part of the figure is going to be the area of the square minus the combined area of the circles. All of the circles are the same size, so we can say that:
\[A = l ^{2} + 9(\pi r ^{2})\]
Where l is the length of one of the square's sides. Since the square is three circles wide, we can use
l = 3d
to find the length of one side, where d is the diameter of one circle.

4. This is a circumference problem. I don't know how to explain it, but the equation would be:
d = 10C or d =10(2pi*r)
Where d is the distance.