Download Angles First Lesson Quadrilateral = a 4 sided figure Parallelogram

Angles First Lesson
Quadrilateral = a 4 sided figure
Parallelogram = a quadrilateral with two sides parallel
Trapezium = a parallelogram with a third side at right angles to the parallel sides
Rectangle = a trapezium with the all sides at right angles to each other
Square = a rectangle with each side having the same length.
Triangles are 3 sided figures
Scalene Triangle = a triangle with three sides of different lengths
Isosceles Triangle = a triangle with two sides the same length
Equilateral Triangle = a triangle with three sides the same length
Right Angled Triangle = a triangle with one right angle in it (Pythagoras)
Angles
Symmetry = it looks the same after you do something to it, e.g. rotate it or hold a mirror to it
Congruent = two shapes which have the same shape, the same size
Right angled = like the corner of a page, square.
Lines, and Shapes
Lines go on forever, well beyond the edge of the page. Line segments are chopped up bits of
lines and have a length.
Vertex (vertices) are the points on a shape, three points on the triangle, four on a square etc.
Pentagon, Hexagon, Octagon.... are names of some polygons. You can call them n-gons (n=
5,6,8) but that’s not very interesting.
A plane is a flat bit of space but in maths it does not help a door to fit into its frame. A Compass
in maths draws circles and doesn’t usually know which direction is North. Only two points are
needed to define a line, if there are lots of points on a line they’re collinear. The middle point of
a line segment is called the midpoint (no imagination these mathematicians...) A protractor is a
usually a D shape and gives the size of angles. Euclid proved lots of things about angles about
2300 years ago and made some proofs about numbers too. (He showed that you can’t make a list
of all the prime numbers.) Why do we have 360 degrees in a full rotation? It is because the
Babylonians used them? The Persians used them? Who knows? There was an attempt to
decimalize angles so that 100 grad were a right angle. It’s still on your calculator but no one used
them.
http://www.mathsisfun.com/definitions/congruent.html