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 radius#6#
has a Cartesian equation
#color(white)("XXX")(x-0)^2+(y-4)^2=6^2# - Circle B with center
#("(-3,5))# and radius#24#
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 coordinate#x# value has#a# added to it; and
every coordinate#y# value has#b# added to it.Applications
Applying a translation of#vec(""(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 of#vec(""(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 by#color(black)(d)# Application
(note for the equation of a circle, only the radius is a#underline("distance")# measurement).
Applying a dilation of#4# 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.