SOLUTION: The centers of two circles are 25 units apart. The radius of one circle is 11 and the radius of the other circle is 4. What is the length of the common external tangent? I'm having

Algebra ->  Circles -> SOLUTION: The centers of two circles are 25 units apart. The radius of one circle is 11 and the radius of the other circle is 4. What is the length of the common external tangent? I'm having      Log On


   

Question 859346: The centers of two circles are 25 units apart. The radius of one circle is 11 and the radius of the other circle is 4. What is the length of the common external tangent? I'm having trouble with drawing the diagram and starting out the problem.
Answer by mananth(16946) About Me  (Show Source):
You can put this solution on YOUR website!
Let P & Q be the centers of the two circles
let MN be the tangent to both circles
Draw PM & QM the radii parallel to each other
From Q draw a parallel to MN to touch PM at T
So PTQ is a right triangle
angle PTQ = 90
PQ is the hypotenuse
which is 25 units
PT = 11-4 = 7 units
Using Pytahgoras theorem
25^-7^2= QT^2
576=QT^2
QT=24
But QT = MN
there fore MN = 24 units
Draw the figure you will walk through