O and O' are the centres of two circles with radii 7 cm and 9 cm resp. The distance between the centres is 20 cm, if PQ be the transverse common tangent to the circles, which cuts OO' at X . What is the length of O'X?
a. 35/4
b. 45/4
c. 10
d. 11

• by similarity of triangle
  9/7=ox'/(20-ox')
  =>ox'=45/4
• 10 years agoHelpfull: Yes(11) No(1)
• by similarity of two trianges
  r1/r2=ox/ox' the distance bw both circles circumferences will be 4
  7/9=7+x/13-x(9+4-x)
  x=7/4 so 4-x=9/4
  0'x=9+9/4=45/4cm
• 10 years agoHelpfull: Yes(4) No(0)
• similarity of triangle
  9/7=ox'/(20-ox')
  =>ox'=45/4=11.25
• 10 years agoHelpfull: Yes(1) No(0)
• by similarity of triangle
  9/7=o'x/(20-o'x)
  => o'x=45/4
• 10 years agoHelpfull: Yes(1) No(0)
• by similarity of triangles,9/7=ox'/(20-ox')=>ox'=45/4
• 10 years agoHelpfull: Yes(1) No(0)
• 45/4 will be the ans
• 10 years agoHelpfull: Yes(1) No(0)
• Ans is 10...triangles made by the two circle are symmetric...
• 10 years agoHelpfull: Yes(0) No(5)
• by similarity of triangles
  (20-x)/x=7/9
  therefore x=45/4
• 10 years agoHelpfull: Yes(0) No(0)
• similarity of triangle
  9/7=ox'/(20-ox')
  =>ox'=45/4=11.25
• 10 years agoHelpfull: Yes(0) No(0)