2012 · Q19
A circular ring with centre O is kept in the vertical position by two weightless thin strings TP and TQ attached to the ring at P and Q. The line OT meets the ring at E whereas a tangential string at E meets TP and TQ at A and B respectively. If the radius of the ring is 5 cm and OT = 13 cm, then what is the length of AB?
Elementary MathematicsGeometry
- A10/3 cm
- B20/3 cm
- C10 cm
- D40/3 cm
Explanation
The tangent from T(13,0) touches the circle x^2+y^2=25 at (25/13, +/-60/13); the tangent line meets x = 5 at y = +/-10/3, so AB = 20/3 cm.