trig

• State the relationship between degrees and radians


  180° = π radians
• Describe how to convert from degrees to radians (2)


  step 1: divide the degrees value by 180 degrees

  step 2: times by π
• Describe how to convert from radians to degrees (2)


  Step 1: multiply the fraction by 180

  Step 2: divide by π
• Draw the exact trig value triangles

  
• State the sinx exact values (5)

  
• State the cosx exact values (5)

  
• State the tanx exact values (5)

  
• Describe the quadrants (CAST order, equations, location of positive and negative values)


  ASTC order

  A = All (0-90)

  S = 180 - x (90-180)

  T = 180 + x (180 - 270)

  C = 360 - x (270 - 360)

  They are all positive in their quadrant
• Describe the process for solving trig equations where the co-efficent of x is greater than one (eg tan2x 0<x<360)


  step 1: solve the equation to find 2x (or whatever value is given)

  step 2: find the quadrant value (in ex 180+2x)

  step 3: divide values of 2x by 2 (or whatever value is given)

  step 4: add 180 to the values until you get to the required angle (in ex 360)
• Describe the process for solving trig equations where the x value is squared (eg sin²x)


  step 1: square root the other side of the equation

  step 2: recognise that it is ± because a square root can be either

  step 3: find all four quadrant values
• How to use addition and subtraction formulae when given expressions such as tanA=2/5 with cosB=12/13.


  draw the triangles to match the expressions and use them to find the values
• When solving equations using the double angle formulae what does it mean if the value found for cosx or sinx is greater than 1 or less than -1


  there are no solutions, since the graph doesnt exit this area