Form 1 Mathematics Chapter 6

 Lesson requirement  Textbook 1A  Workbook 1A  Notebook  Folder  Before lessons start  Desks in good order!  No rubbish around!  SHW (II)  Today!!!!!

 Basic concepts of Geometry  Points 點  Lines 線  Planes 面  (Solids) 體  Other concepts of Geometry  Angles 角  Parallel Lines 平行線  Perpendicular Lines 垂直線

 Points 點  Lines 線  Planes 面

 Angles:  Name of angles (middle letter is vertex!)

 There are six types:

 When two lines in the same plane, but they do not intersect each other, they are called parallel lines ( 平行線 )  A pair of parallel lines is denoted by a pair of arrows ( 箭號 )  We write “AB // CD”

 When two lines in the same plane are intersecting at right angle (90  ), they are called perpendicular lines ( 垂直線 )  A right angle will be clearly shown in a pair of perpendicular lines  We write “AB  CD”

 Any shape enclosed by line segments in the same plane is called Plane Figure.  Otherwise, it should be a curved surface.

 The name of the polygons depends on the number of straight lines:  Triangle3 lines(Tri-)  Quadrilateral4 lines(Quadri-)  Pentagon5 lines(Penta-)  Hexagon6 lines(Hexa-)  Octagon? lines(Octa-)  Number prefix (from wikipedia) Number prefix

 Diagonal ( 對角線 ) is the line segment joining any two non-adjacent ( 不相鄰 ) vertices ( 頂點 vertex)  A line segment joining two adjacent vertices is called a side ( 邊 )  Same side  Equilateral ( 等邊 ) polygon  Same angle  Equiangular ( 等角 ) polygon  Both  Regular polygon ( 正多邊形 )

 Parallel lines: p.231  Perpendicular lines:p.232  Circle:p.236  Triangles:p.241

 All points on the circle (circumference 圓周 ) are at the same distance (radius 半徑 ) from the a fixed point (centre 圓心 ).  Diameter ( 直徑 ) is 2 x Radius (d = 2r)  C = d x  ( 圓周率 ) or C = 2  r    … r C d

 Triangles are formed by three straight lines  Its name depends on its angles

 Sum of angles of a triangle is 180   a + b + c = 180  (Straight angle = 180  )

 Page 246 of Textbook 1A  Questions 15 – 17  Pages 112 – 113 of Workbook 1A  Questions 3 and 5

 Solids are 3-D (three-dimensional) figures. Plane Vertex Edge Curved surface

 Dotted lines  Isometric Drawing 1 cm

 If we cut a solid at right angle to its length, the plane is called a cross-section.  If planes from the parallel cuts are the same, the plane is a uniform cross-section

 When all faces of a solid are polygons only, it is called a polyhedron. Yes! No!

 The connected planes of a polyhedron are called a net.

 Drawing Exercise  Class Activities I – IV  Pages 256 – 257 of Textbook 1A  Questions 4 – 11  Pages 118 – 120 of Workbook 1A  Questions 4 – 6

 Drawing Exercise  28 Jan (Mon)  Dictation – words on the PowerPoint files  29 Jan (Tue)  SHW (III) – Chapter 6  30 Jan (Wed)  OBQ – Chapter 6  30 Jan (Wed)  CBQ – Chapter 6  1 Feb (Fri) or 6 Feb (Wed)

Enjoy the world of Mathematics! Ronald HUI