3. From the top of a 9 metres high building AB, the angle of elevation of the top of a tower CD is 30º C and the angle of depression of

• incomplete ques
• 11 years agoHelpfull: Yes(4) No(6)
• From the top of a 9 metres high building AB, the angle of elevation of the top of a tower CD is 30º and the angle of depression of the foot of the tower is 60º. What is the height of the tower?
  Ans:
  
  
  
  We have to find the value of CD. We use Sine rule to find the answer easily. Sine rule is aSinA=bSinB=cSinC
  
  In triangle BDE, 9Sin60=xSin30
  
  So 93√2=x12⇒x=93√
  
  In triangle BCD, CDSin30=93√Sin60
  
  CD12=93√3√2⇒CD=3
  So height of the tower = 9 + 3 = 12
• 8 years agoHelpfull: Yes(1) No(0)