Shortcut Trick
Sum the ratios: a2+b2 + b2+c2 + c2+a2 = 34 + 61 + 45 = 140.
Then a2+b2+c2 = 140 ÷ 2 = 70.
Individual squares: a2 = 70 − 61 = 9, b2 = 70 − 45 = 25, c2 = 70 − 34 = 36.
Roots: a = 3, b = 5, c = 6.
Required ratio: (3+5) : (5+6) : (6+3) = 8 : 11 : 9.
∴ The correct answer is 8 : 11 : 9.
Alternate Method
Given: (a2 + b2) : (b2 + c2) : (c2 + a2) = 34 : 61 : 45
Calculations:
⇒ Let a2 + b2 = 34k, b2 + c2 = 61k, and c2 + a2 = 45k.
⇒ Adding all three: 2(a2 + b2 + c2) = (34 + 61 + 45)k = 140k.
⇒ a2 + b2 + c2 = 70k.
⇒ a2 = (a2 + b2 + c2) − (b2 + c2) = 70k − 61k = 9k → a = 3√k.
⇒ b2 = (a2 + b2 + c2) − (c2 + a2) = 70k − 45k = 25k → b = 5√k.
⇒ c2 = (a2 + b2 + c2) − (a2 + b2) = 70k − 34k = 36k → c = 6√k.
⇒ a + b = 3√k + 5√k = 8√k.
⇒ b + c = 5√k + 6√k = 11√k.
⇒ c + a = 6√k + 3√k = 9√k.
⇒ (a + b) : (b + c) : (c + a) = 8√k : 11√k : 9√k = 8 : 11 : 9.
∴ The correct answer is 8 : 11 : 9.
Additional Information
Sum of Ratios Property
For equations involving sums of pairs like x+y, y+z, and z+x, adding all equations and dividing by 2 gives the total sum x+y+z.
Ratio to Square Root
When terms are in square form, the ratio of the variables is found by taking the square root of the ratio constants, provided the numbers are positive.
Compound Ratio
The ratio of the sums (a+b):(b+c):(c+a) is derived from individual values calculated through the method of substitution or comparison from the total sum.