section 5 angles and geometry

section 5 angles and geometry

1. angles names

   • acute angle
     • less than 90
   • right angle
     • exactly 90
   • obtuse angle
     • between 90 and 180
   • reflex angle
     • bends back more than 180

2. angle notation

   • for example acb
     • the middle letter is where the angle is
     • the other two letters tell you which 2 angles enclose the angle

3. five angle rules

   • angles in triangle add up to 180
   • angles in straight line add up to 180
   • angles in quadrilateral add up to 360
   • angles round a point add up to 360
   • isolies have 2 sides the same and two and to angles the same
   • example page 73

4. parallel lines

   • the two bunches of angles are the same
   • there are only 2 different angles a small one and a big one
   • these always add up to 180
   • example page 74

5. different types of angles

   • alternate angles
     • they are the same found in a z shape
   • interior angles
     • they add up to 180 they are found in c or u shape
   • corresponding angles
     • they are the same they are found in a f shape
   • examples and diagram page 74 and 75 and 76

6. angles at the centre

   • the angle at the centre of a regular polygon is the same as the exterior angles

7. sum of interior angles

   • (n-2)x180
   • this works for all polygons
   • examples on 77

8. read pages 78-79 transformations and reflection and rotation

   • read 80-81

9. pythagoras thorem

   • 1) first square the two number given
     • 2) then to find long side add the squared numbers
       • to find the short side subtract the squared numbers
         • once you have the answer square root it and that is the answer
   • for examples of this look on page 86