trigo expert!

• usck

  1 Apr 07, 23:44

  
  
  why vertical force use SIN and not COS?
  
  
• airgrinder

  1 Apr 07, 23:48

  Originally posted by usck:

  
  
  why vertical force use SIN and not COS?
  
  

  SIN or Cos all can lah. Depends which angle you looking at.
  
  sin x = cos (90-x)
• akinos

  2 Apr 07, 00:00

  Its resolving vectors in the vertical (y) and horizontal (x) component. You should know that if u are doing this question.
• walesa

  2 Apr 07, 02:11

  Originally posted by usck:

  
  
  why vertical force use SIN and not COS?
  
  

  Angle C is between F= Thrust and the Horizontal Axis --> FcosC actually gives you a force in the direction of the horizontal axis. If you need the force in the vertical direction (ie.angle between F = Thrust and the Vertical Axis), that's effectively Fcos(90deg-C) or FsinC...
• the.owl

  2 Apr 07, 03:02

  depends on which angle, noob.
• Xcert

  2 Apr 07, 10:45

  Originally posted by usck:

  
  
  why vertical force use SIN and not COS?
  
  

  because when U resolve the forces into x and y axis...U need to know the critical angle for the sin and cos...once U know the critical angle...sin or cos doesnt really matter.
  
  cos C=sin(90-C), where C is the critical angle, known as climb angle in ur pic.
  
  And it would be useful to know the 4 quadrants of trigo.