SOLUTION: two circles radii a&b(a>b) touch each other externally.St is a common tangent touching the circles at S&T respectively. then ST^2=?

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Question 768538: two circles radii a&b(a>b) touch each other externally.St is a common tangent touching the circles at S&T respectively. then ST^2=?
Answer by mananth(16946) About Me  (Show Source):
You can put this solution on YOUR website!
The radii of the circle are a & b a>b
The distance between their centers = a+b
a tangent drawn from the smaller circle parallel to the above line will be equal to (a+b)
a-b is the difference between the two radii
ST^2 = (a+b)^2+(a-b)^2
ST%5E2+=+a%5E2%2B2ab%2Bb%5E2%2Ba%5E2-2ab%2Bb%5E2
ST^2= 2(a^2+b^2)