發送短信 : A unified method of teaching conic sections

  ______    _____     _____      ___      _  _   
 /_____//  |  ___||  |__  //    / _ \\   | \| || 
 `____ `   | ||__      / //    / //\ \\  |  ' || 
 /___//    | ||__     / //__  |  ___  || | .  || 
 `__ `     |_____||  /_____|| |_||  |_|| |_|\_|| 
 /_//      `-----`   `-----`  `-`   `-`  `-` -`  
 `-`