Mrs. Brenda Overholt
Math Department
Franklin County High School
700 Tanyard Road
Rocky Mount, Virginia 24151
Choosing the Trig Function
 
All right triangle trigonometry problems use this formula: 
Rule: The trig function is based on the two sides you decide to use.  Replace TrigFunction in the formula with either sin, cos, or tan.
Choice: There are three of them! 
  • Decide where you'll be standing
  • Look at the sides you have in the problem. 
  • Decide which two you'll be using (Hint) 
  • Then using Oscar or Sohcahtoa, decide which trig function would be best.
 
sin 36  cos 36  tan 36 
  • Decide where you'll be standing
  • Look at the sides you have in the problem. 
  • Decide which two you'll be using (Hint) 
  • Then using Oscar or Sohcahtoa, decide which trig function would be best.
 
sin x  cos x tan x 
  • Decide where you'll be st__________.
  • Look at the si___ you have in the problem. 
  • Decide which two you'll be using (Hint) 
  • Then using Oscar or Sohcahtoa, decide which trig f_______ would be best.
 
sin 50  cos 50  tan 50 
This problem is a little different.  You might choose to stand at M or N.  BUT either way, the trig function will be the same!  Which one?
 
sin x or sin y  cos x or cos y  tan x or tan y 
 
Next: Setting up a Trig Function equation
[ tutorial | examples | standing choice | function choice | equation ]
brenda.overholt@frco.k12.va.us
August, 2004