A has center of (0, 4) and a radius of 6, and circle B has a center of (-3, 5) and a radius of 24. What steps will help show that circle A is similar to circle B?
1 Answer
Two circles are similar because they have the same shape: they are both circles.
It's difficult to see what this question is asking. Perhaps the Explanation below is what is being looked for.
Explanation:
Two shapes are similar if by applying
- translation (shift);
- dilation (resizing);
- reflection; and/or
- rotation
they can be mapped into identical forms.
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Note that
- Circle A with center
(""(0,4)) and radius6
has a Cartesian equation
color(white)("XXX")(x-0)^2+(y-4)^2=6^2 - Circle B with center
("(-3,5)) and radius24
has a Cartesian equation
#color(white)("XXX")(x+3)^2+(y-5)^2=24^2
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In the Cartesian plane:
translation (shift) of
color(black)(vec(""(a,b))
Every coordinatex value hasa added to it; and
every coordinatey value hasb added to it.Applications
Applying a translation ofvec(""(color(red)(0),color(blue)(4))) to circle A
gives the circle A' with the equation:
color(white)("XXX")((xcolor(red)(0))-0)^2+((ycolor(blue)(+4))-4)^2=6^2
color(white)("XXX")rarr x^2+y^2=6^2
Applying a translation ofvec(""(color(red)(3),color(blue)(-5))) to circle B
gives a circle B' with the equation:
color(white)("XXX")((xcolor(red)(+3))-3)^2+((ycolor(blue)(-5))+5)^2=24^2
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dilation of
color(black)(d)
Distances from the origin are multiplied bycolor(black)(d) Application
(note for the equation of a circle, only the radius is aunderline("distance") measurement).
Applying a dilation of4 to the equation of Circle A'
gives the circle A'' with equation
color(white)("XXX")x^2+y^2=(6xx4)^2
color(white)("XXX")rarr x^2+y^2=24^2
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Since the equations for A'' and B' are identical
and
Circle A'' is the same as Circle A after translation and dilation
and
Circle B' is the same as Circle B after translation.