circles properties..

• Fireindahouse

  2 Oct 07, 15:12

  
  
  i need help with part b(iii) pretty pls.
  
• wishboy

  2 Oct 07, 15:36

  (a) 90° (angle in semicircle)
  
  (b)
  (i)
  sin angleOAB = 6/13
  angleOAB = 27.5°
  
  (ii)
  tan 27.486° = 15/AC
  AC = 28.8 cm
  
  (iii)
  sin 27.486° = ½CE/28.832
  CE = 26.6 cm
  
  for part (iii), there is another right angle triangle formed by the tangent and the vertical line across the big circle
• davidche

  2 Oct 07, 17:53

  Im too lazy to do for you.
  
  Some pointers, the tangents are right angled to the radius.
  the whole figure is full of similar figures.
  try using simple pythagares(sp.).