BEARINGS

• The bearing of a point B from another point A is:
  • an angle measured from the north at A.
  • in a clockwise direction.
  • written as a three-figure number (i.e., 000° to 360°)
  • For example, the bearing of B from A is 050°
    

PYTHAGORAS THEOREM

• To find the hypotenuse, c: c² = a² + b²
• To find one of the shorter sides:
  • a² = c² – b²
  • b² = c² – a²

• Angle of elevation: is the angles above the horizontal line.
• 
• Angle of depression: is the angle below the horizontal line.

• Area of a triangle = ^ab/₂ sin c

• Ratios
  • Right angled Triangles:
    • 
    • sin x = ^opposite/_hypotenuse [SOH]
    • cos x = ^adjacent/_hypotenuse [CAH]
    • tan x = ^opposite/_adjacent [TOA]

• Sine Rule
  • ^a/_{sin a} = ^b/_{sin b} = ^c/_{sin c}
  • One pair of information needed.
• Cosine Rule
  • To find the angle when given 3 sides: cos a = ^{(b2 + c2 – a2)}/_2bc
  • To find a side when given the angle and two sides: a² = b² + c² – 2bc cos a