Three mutually tangent circles

In summary, to find the value of r, you need to use the relationship between the radius and the angle of each sector and the area of the shaded part, which is equal to 24 square units. By knowing the angle of each sector and the area of the triangles, you can determine the value of r using the formula r=sqrt(360*area of sector/60pi).
  • #1
Megrs
8
0

Homework Statement



Three mutually tangent circles with the same radius r enclose a shaded area of 24 square units. Determine the value of r to the nearest unit.

Homework Equations


do i use the arc length formula to find the answer?


3. The Attempt at a Solution

A=(central angle*pi*r^2)/360
the central angle is 60 because if u draw a triangle between the three centers of the circles it is equilateral...but i don't know how to get r with only this information
 
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  • #2
Hi Megrs@! :smile:

(have a pi: π and a degree: ° and try using the X2 tag just above the Reply box :wink:)
Megrs said:
Three mutually tangent circles with the same radius r enclose a shaded area of 24 square units. Determine the value of r to the nearest unit.

the central angle is 60 because if u draw a triangle between the three centers of the circles it is equilateral...but i don't know how to get r with only this information

You're almost there!

Stay with that triangle …

it has the shaded area inside it, so what's left? :wink:
 
  • #3
tiny-tim said:
Hi Megrs@! :smile:

(have a pi: π and a degree: ° and try using the X2 tag just above the Reply box :wink:)


You're almost there!

Stay with that triangle …

it has the shaded area inside it, so what's left? :wink:

what is left are the sectors of the circles and if u make each one=x then 3x+24=A of the triangle. the arc length is r(2*pi*central angle/360) i don't think that gives any useful information though...except maybe help prove the answer once i find it...
 
  • #4
Hi Megrs! :wink:

(what happened to that π i gave you? :confused:)

Yes, three sectors …

now, you know the radius and the angle of each sector, so the area is … ? :smile:
 
  • #5
tiny-tim said:
Hi Megrs! :wink:

(what happened to that π i gave you? :confused:)

Yes, three sectors …

now, you know the radius and the angle of each sector, so the area is … ? :smile:

what n?? i don't get it...
no, i know the angle of the sectors...i do NOT know the radius that is what i have to find...so i don't know the area of the sectors either
 
  • #6
(it's not an "n", its a "π" !)

Yes, but you know that r is half the side of your equilateral triangle! :wink:

so the area of the shaded part (as a multiple of r) is … ? :smile:
 
  • #7
i know r is half the side i don't get how to relate this all together because the shaded part is not part of the circles...the area of the shaded part is 24. the area of a sector is (24-area of the triangle)/3...
 
  • #8
so as a factor of r, the area of a sector is … ? :smile:
 
  • #9
tiny-tim said:
so as a factor of r, the area of a sector is … ? :smile:

area of a sector is 60*r^2*pi/360
 
  • #10
Megrs said:
area of a sector is 60*r^2*pi/360

so as a multiple of r, the area of the shaded part is … ? :smile:
 
  • #11
i don't know because the shaded part is not part of the sectors...
r=sqrt(360*area of sector/60pi)
?
 

1. What are three mutually tangent circles?

Three mutually tangent circles are three circles that intersect each other at exactly one point, where each circle is tangent to the other two. This means that they share a common tangent line at the point of intersection.

2. How are the radii of three mutually tangent circles related?

The radii of three mutually tangent circles are related by a specific ratio known as the triple tangent ratio. This ratio is equal to the product of the three radii divided by the sum of the products of each pair of radii. In simpler terms, it can be written as (r1*r2*r3)/(r1*r2 + r2*r3 + r1*r3).

3. What is the significance of three mutually tangent circles in mathematics?

Three mutually tangent circles have various applications in mathematics, including in geometry, trigonometry, and complex analysis. They are also used in various engineering and design problems, such as finding the optimal size and position of three intersecting pipes or cables.

4. How can the centers of three mutually tangent circles be determined?

The centers of three mutually tangent circles can be found by drawing the common tangent lines between each pair of circles and finding the intersection point of these lines. This point will be the center of all three circles.

5. Can three mutually tangent circles have different radii?

Yes, three mutually tangent circles can have different radii. However, the triple tangent ratio will still hold true and the radii will be related in a specific way. The radii can also be equal, which would result in three identical circles.

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