F.1 Mathematics Supplementary Notes Chapter 8 & 10 4/2002 Chapter 8 Introduction to Geometry Chapter 10 Congruence and Similarity Important Terms Geometry line segment end point point of intersection acute angle right angle obtuse angle congruent to 幾何學 線段 端點 交點 銳角 直角 鈍角 全等於 Name:___________( isosceles triangle equilateral triangle polygon regular polygon parallel lines perpendicular lines diagonal proportional 等腰三角形 等邊三角形 多邊形 正多邊形 平行線 垂直線 對角線 成比例 centre circumference diameter radius solid cross-section vertices similar to )Class: F.1 ( 圓心 圓周 直徑 半徑 立體 橫切面 頂點 相似於 Exercise 1 1. Refer to the figure A D C B (a) Produce(延長) BA and CD to meet at P. (b) Produce BC to Q so that the length of CQ is less than that of BC. (c) Join AQ to meet the line segment CD at M. (d) Join the two diagonals AC and BD,and mark the point of intersection by F. 2. Refer to the figure Angle E Kind (a) ABF (b) EBA (c) FBC (d) b acute angle ___________ ___________ ___________ (e) ABC (f) EBD ___________ ___________ b D 250 F 400 A B P. 1 C ) F.1 Mathematics Supplementary Notes 3. Chapter 8 & 10 4/2002 In the figure, AB=BC=CA=CD. A (a) The isosceles triangles are _________________________ and an equilateral triangle is _________________________ (b) ACB=__________________ D E d 70 0 b B C (c ) b + d = __________________ 4. Find the unknown in each of the following triangles. (a) (b) 3x 29 0 x–5 0 x a 27 0 (c) (d) 48 b 41 0 17 x *5. In the figure DCA=DCB , DBA=DBC , BAC=64, find x. A 64 D x B C P. 2 F.1 Mathematics Supplementary Notes Chapter 8 & 10 4/2002 P. 3 Exercise 2 1. In each of the following pair of triangles, decide whether ABC is congruent to the other For each pair of congruent triangles, give the abbreviated reference. (a) (b) AB = FD BC = DE AC = FE ABC FDE (SSS) (c) (d) (e) (f) triangle or not. F.1 Mathematics Supplementary Notes (g) 2. Chapter 8 & 10 (h) In each of the following, find out which two of the given triangles are congruent and give the abbreviated reason. 4/2002 P. 4 F.1 Mathematics Supplementary Notes Chapter 8 & 10 4/2002 P. 5 F.1 Mathematics Supplementary Notes Chapter 8 & 10 4/2002 Conditions for Similar Triangles ∠BAC=∠QPR ∠ABC=∠PQR ∠BCA=∠QRP (equiangular) ( or AAA) (3 sides prop.) ∠ACB=∠PRQ (2 sides prop. inc. eq.) Exercise 3 1. In each of the following, state whether the given pair of triangles are similar or not. For each pair of similar triangles, give the abbreviated reference. ABC RPQ (3 sides prop.) Reasoning Steps CB 5 1 QP 15 3 BA 4 1 PR 12 3 CA 3 1 QR 9 3 CB BA CA 1 QP PR QR 3 ABC RPQ (3 sides prop.) P. 6 F.1 Mathematics Supplementary Notes 1. Chapter 8 & 10 4/2002 A 2. A Y X Z Y Z C B C 3. A P Q Z C 4. R B B X Q A B C P R P. 7 F.1 Mathematics Supplementary Notes 5. Chapter 8 & 10 X 4/2002 6. A C Z X B Y C A Z Y B 7. 8. 9. 10. 11. 12. P. 8 F.1 Mathematics Supplementary Notes Chapter 8 & 10 13. 14. 15. 16. 17. Given that ABC XYZ, BAC = 1230, ABC = 250, AB = 6cm, XY = 2cm, YZ = 3.2cm, find (a) XYZ (b) YZX (c) BC. 4/2002 P. 9 F.1 Mathematics Supplementary Notes Chapter 8 & 10 4/2002 P. 10 18. Given that ABC DEF, AB = 3cm, AC = 5cm, BC = 7cm, EF = 8.4cm, BAC = 1200, find (a) FDE (b) DE (c) DF. Level II 19. In each of the following, find out which two of the given triangles are similar and prove it. 20. (a) (b) In each of the following, find out a pair of similar triangles and prove it, hence find the value(s) of the marked unknowns. F.1 Mathematics Supplementary Notes (c ) (d) (e) Chapter 8 & 10 4/2002 P. 11 F.1 Mathematics Supplementary Notes Chapter 8 & 10 4/2002 P. 12 F.1 Mathematics Supplementary Notes Chapter 8 & 10 4/2002 P. 13 F.1 Mathematics Supplementary Notes Chapter 8 & 10 4/2002 P. 14