Form 1 Mathematics Chapter 6

 SHW (III), Re-dictation & OBQ  Today  SHW (I), Dictation, Re-dictation Correction  1 Feb (Fri)  SHW (II), (III), Drawing, OBQ Correction, Bring Textbook, Workbook 1B  4 Feb (Mon)  CBQ  6 Feb (Wed)

 Here are the answers:  1. 線段 Line Segment  2. 頂點 Vertex  3. 平行線 Parallel Lines  4. 垂直線 Perpendicular Lines  5. 鈍角 Obtuse Angle  6. 等腰三角形 Isosceles Triangle

 Next we have:  7. 圓周 Circumference  8. 直徑 Diameter  9. 對角線 Diagonal  10. 正多邊形 Regular Polygon  11. 等邊五邊形 Equilateral Pentagon  12. 等角六邊形 Equiangular Hexagon  Correction: 10 times

 Give the English name of the followings:  1. 銳角  2. 反角  3. 平面圖形  4. 曲面  5. 半徑  6. 相交

 Give the English name of the followings:  7. 四邊形  8. 多面體  9. 等距畫圖  10. 均勻橫切面  11. 等邊三角形  12. 全等八角形  Can you get them all?

 Here are the answers:  1. 銳角 Acute angle  2. 反角 Reflex angle  3. 平面圖形 Plane figure  4. 曲面 Curved surface  5. 半徑 Radius  6. 相交 Intersect

 Next we have:  7. 四邊形 Quadrilateral  8. 多面體 Polyhedron / Polyhedra  9. 等距畫圖 Isometric drawing  10. 均勻橫切面 Uniform cross-section  11. 等邊三角形 Equilateral triangle  12. 全等八角形 Regular octagon  Can you get them all?

 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-)  Octagon8 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 )

 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  )

  Sum of  : a + b + c = 180 

 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 Exercises & Dictation  Today!!!!  SHW (III) & OBQ  30 Jan (Wed)  SHW (I), (II), Dictation Correction  1 Feb (Fri)  SHW (III), OBQ Correction  4 Feb (Mon)  CBQ  6 Feb (Wed)

Enjoy the world of Mathematics! Ronald HUI