Two circles touch each other eternally .Their centres are at a distance of 11cm. The sum of the areas of the circles is 65 pie square cm . Find their radii
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1
Step-by-step explanation:
two circles are touch eternally,if the radii ate x cm,y cm then x-y=11
πx^2+πy^2=65π
x^2+y^2=65
(x-y)^2+2xy=65
2xy=65-11^2=65-121= -56
(x+y)^2=(x-y)^2+4xy
=121-112=9
x+y=3
x-y=11
2x=14,x=7
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Answer:
the radii are 7cm and 4cm
Step-by-step explanation:
a + b = 11
sum of their areas
π^2a + π^2b = 65π
a^2 + b^2 = 65
we know that b = 11 - a
a^2 + (11 - a) ^2 = 65
2a^2 - 22a + 56 =0
a^2 - 11a + 28 =0
a = 7 .......1
b = 11 - 7 = 4
the two radii are 7cm and 4cm
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