Questions on Geometry: Circles and their properties answered by real tutors!

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Question 207908: Hi! I've been trying to solve this but i have no idea how. Please help me!
find the equation of the circle with center at y-axis and which passes through the origin and the point (4,2)

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Question 207911: A circle has an area of 12.56 in squared. What is its radius?
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Question 209195: Find the circumference and area of a circle with radius of 5 centimeters. Write your answers in terms of pi.
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Question 209376: I would be very appreciated if someone were to help me answer this problem. A circular planetarium has a center stage with a 9 foot radius and five outer rings of circles of seats. Each ring of seats is seven feet wide. What is the circumference of the largest circle?
C=2*pi*r

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Question 209636: Drawing: Rectangle containing 8 circles of equal size (4 on top row, 4 on bottom row)
Problem: Find the area of the rectangle if the radius of each circle is 3
What I know: The area of a circle is A=IIr^2 / A=3.14 x 3^2 / A=3.14 x 9 / A=28.26 so the area of the 8 circles would be 28.26 x 8=226.08, but is that really the area of the rectangle that contains the circles? Is there a formula for finding this answer?
Thank you for your help!

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Question 209829: A circle is inscribed in triangle ABC. If AB=6 inches, BC=8 inches, and AC=10 inches, find CR.
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Question 210713: The area of a circular ring is 90. If the radius of the outer circle forming the ring is 10, what is the radius of the inner circle of the ring? (assuming the circles forming the ring have the same center.)
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Question 211114: This isn't really a math homework question, but I need it for measuring a dress.
I need to cut out a circle with a 35 inch circumfrence for the bust of the dress. I don't know the radius or diameter, just that one measurment. Is there any way you can help?

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Question 211733: A square barn measures 14 meters on each side. A goat is tethered outside by a rope that is attached to one corner of the barn. The rope is 8 meters long.
Suppose the rope is made twice as long. On how many sqaure meters of land is the goat now able to graze?
Lastly, an addition to the barn was built making it rectangular with dimensions 14 by 20 meters. On how many square meters of land is the goat now able to graze?

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Question 212045: what is the diameter of a circle whose circumference is equal to 20 inches
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Question 213076: i have 4 circle all have a radius of 10' they all are touching each other in a square patern what is the square feet of the space in the center of the 4 circles
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Question 213175: Find the area of the shaded region. The center of all the circles is point D.
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Question 213392: Area of circular ring
A=2pi(P)(w) Solve for P
Find P given A=22cm^ and w=2cm

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Question 214271: Find the equation of each circle described.
Passes through the origin and is concentric with the circle x^2-6x+y^2-4y+4=0

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Question 214271: Find the equation of each circle described.
Passes through the origin and is concentric with the circle x^2-6x+y^2-4y+4=0

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Question 206837: Could someone tell me if this is right?
Problem; What is the equation of the ellipse with foci at (0,-4) and (0,4) and the sum of its focal radii being 10?
My answer; 2a=10 a=5 (sum of focal radii)
(0+0/2, (4+4/2)= (0,4)
c=4 b^2=a^2-c^2=25-16=9
equation of the ellipse is;
(x-0)^2/25+(y-4)^2/9=1

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Question 215374: Thank you for your time. We are looking for the circumference length for a 60ft. circle. I've forgotten the formula. Thank's again, Scott
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Question 215925: I have a square that is inscribed into a circle. The area of the square is 64 square centimeters. I need to find the area of the shaded portion of the circle. The square touches the circle at each corner. Between each corner, there is the shaded area (from corner to corner to the outside edge of the circle.
I hope this makes sense.

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Question 216562: three concentric circles have the centers at O
OABC is a rectangle C lies on the middle circle
A lies on the center circle and B lies on the outer circle the radius of the center circle is three Find;area of center circle pi times 9
area of middle circle impossible
area of outer circle dont know

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Question 217030: I have a circle w/ a diameter of 32" What is the circumfrance?
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Question 218208: coordinates of (4,3). What is the circumference of the circle?
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Question 218380: I am trying to make a tire cover and know that the tire has a diameter of 24 and 1/4 inches. What is the length around the circle?
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Question 219100: A circle is drawn in a square whose side has a length of 40. Find the area of the shaded region in terms of pie.
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Question 220101: I've tried this a couple different ways, but the answer wasn't right.
I know that the standard equation for a circle with the center at the origin is
X^2 + Y^2= r^2
but I can't figure out how to find the radius.
Center at origin and containing the point (-2,3)
I've tried using the midpoint formula, distance formula and also inputing the given point into the standard equation for which I got 15. But I'm supposed to end up with 13 for the radius. What am I doing wrong?

Click here to see answer by susanaramya(12) About Me 
Question 220101: I've tried this a couple different ways, but the answer wasn't right.
I know that the standard equation for a circle with the center at the origin is
X^2 + Y^2= r^2
but I can't figure out how to find the radius.
Center at origin and containing the point (-2,3)
I've tried using the midpoint formula, distance formula and also inputing the given point into the standard equation for which I got 15. But I'm supposed to end up with 13 for the radius. What am I doing wrong?

Click here to see answer by nerdybill(7384) About Me 
Question 220101: I've tried this a couple different ways, but the answer wasn't right.
I know that the standard equation for a circle with the center at the origin is
X^2 + Y^2= r^2
but I can't figure out how to find the radius.
Center at origin and containing the point (-2,3)
I've tried using the midpoint formula, distance formula and also inputing the given point into the standard equation for which I got 15. But I'm supposed to end up with 13 for the radius. What am I doing wrong?

Click here to see answer by MathTherapy(10549) About Me 

Question 220208: Points A92,5) and B910,5) are the endpoints of a diameter of a circle graphed in the coordinate plane. How many suare units are in the area of the circle? express you answer as a multiple of "pie"
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Question 220208: Points A92,5) and B910,5) are the endpoints of a diameter of a circle graphed in the coordinate plane. How many suare units are in the area of the circle? express you answer as a multiple of "pie"
Click here to see answer by solver91311(24713) About Me 

Question 221262: I have four circles each with a 10 foot radius, they are put togeather to form a squire of circles what I need to know is the squire foot of the waste in the very middle
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Question 222182: write the equation of the circle in radius-center form with the center at (2,1) and tangent to the line x=5.
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Question 222731: Hannah wants to plant strawberries in a circular plot covering an area of 15 sq meters - write an equation you can use to find the radius
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Question 224919: what is the circumference of a circle with a diameter of 3cm?
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Question 225288: I have a square with 48ft sides what is the area of the base of the largest circular grain bin i can construct. i have the answer but cant figure it out. The first thing i did is 48ft squared it to give me 2304ftsq then im lost
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Question 229541: Two circles have perimeters that add up to 12π centimeters and areas that add up to 20π square centimeters. Find the radius of each circle. Give exact answers.
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Question 229763: Find the center and radius of the circle given by the equation x^2 + y^2 - 8x + 2y - 11 = 0
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Question 229689: ABC is a triangle in which AB=AC. A circle through B touches AC at D intersects AB at P.If D is the mid point of AC, prove that AB=4AP.
Thank You

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Question 195: what does pie equal to. 2
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Question 232659: A large, irrigated crop circle is 400 meters in radius. Correct to the nearest tenth of a hectare, how many hectares of land are contained in this circle.

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Question 232710: a ball has radius of 10 inches. find the surface area. leave the answer in terms of pie.
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Question 232525: Find the circumference of a circle 3.75 ft. Use 3.14 pi and round your answer to one decimal place. I really do not understand how to solve this question. Do I multiply 3.14 with 3.75? I come up with an answer of 1177.50. If this is correct, how then do I convert this answer into ft? Do I move the decimal to 11.77 and the answer is 11.77 ft? Please any help will be appreciated. Thank you.
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Question 233000: suppose the radius of the circle is 3.5 yards. what is the the diameter?
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Question 233000: suppose the radius of the circle is 3.5 yards. what is the the diameter?
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Question 233017: the radius is 7.5 what is the diameter and the circumference
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Question 233317: Two circles, both with the diameter 1.2 meter are placed so that there centers are 0.6 meter apart from each other. How big area does the two circles cover? I have tried to write a picture over it and tried with the formulas for sectors and segments but I can't come up with the right answer. I know it's about 1.82 squaremeters but an explanation would be great.
thanks

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Question 233635: a circular dinner plate has a radius of 13 cm.
calculate the area of the plate.

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