SOLUTION: two circles have diameters which differ by 4.00 cm. if the sum of the areas of the circles is 146.0 cm2, determine their radii

Question 478783: two circles have diameters which differ by 4.00 cm. if the sum of the areas of the circles is 146.0 cm2, determine their radii
Answer by mananth(16946) (Show Source): You can put this solution on YOUR website!
x & x-2 be the radii
pi*x^2+pi*(x-2)^2= 146
/pi
x^2+x^2-4x+4= 146/pi
2x^2-4x+4=146/pi
/2
x^2-2x+2=146/2pi
x^2-2x+2=23.23
x^2-2x-21.23=0
a= 1 ,b= -2 ,c= -21.23
b^2-4ac=
b^2-4ac= 4 - 84.92
b^2-4ac= 88.92 = 9.43

x1=( 2 + 9.43 )/ 2
x1= 5.71
x2=( 2 -9.43 ) / 2
x2= -3.71
Ignore negative value
the radii are 5.72 & 3.72 cm
m.ananth@hotmail.ca
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