Maths equations

• co-interior angles add up to 180 degrees
• alternate angles are equal
• corresponding angles are equal
• vertically opposite angles are equal
• Triangles with three sides are congruent (SSS)
• Triangles with two sides and an angle between them are equal (SAS) Congruent
• Two angles and the side between them are equal (ASA) congruent
• angles in a triangle add to 180 degrees
• SOHCAHTOA:

  S=sin

  O=opposite

  H=hypotenuse

  C=cos

  A=adjacent

  T=tan
• Pythagorean theorem:

  a squared + b squared = c squared
• Area of a triangle = 1/2 ab sin(c)

  Area of a triangle = base x height/2
• Sine rule:

  Sin(a)/A=Sin(b)/B
• Cosine rule: a squared =b squared + c squared - 2 x bc x CosA
• Cosine to find angle:

  b squared + c squared - a squared / 2bc
• The simplest set notation used to represent the elements of a set is the curly brackets e.g{x:x<1}
• x=5 on a number line is drawn vertically parallel to the y axis
• y=5 is drawn horizontally parallel to the x axis
• simultaneous equations:

  solving by elimination means cancelling out one variable by addition or subtraction
• sometimes to solve a simultaneous equation you may need to multiply one of the two equations so that it is possible to eliminate one variable
• Sometimes to solve a simultaneous equation you may need to multiply both equations to then eliminate one variable
• The interior angles of a polygon are always 180 degrees. to find how many sides this polygon will have do the equation 180 degrees x n-2
• Three rules of bearings:

  1. always measure from north
  2. always measure in a clockwise direction
  3. the bearing must always be three digits
• To divide fractions use the KFC method in the correct order

  K=Keep

  F=Flip

  C=Change
• Area of a trapezium = A=a+b/2 x h
• area of a parallelogram A=bh