PowerPoint A)


3B_Ch9(*)

9.1
ABCD DC, BC, A D
9.2

3B_Ch9(*)
ABCD AE = 3 cm DE = 2 cm
EC EB.
9.2
PT ∠SPQ ∠QRS = 130° a
b
9.2



3B_Ch9(*)
AB // DC X AB XC // AD XD // BC XC ⊥ XD XB = 5 cm BC = 3 cm AXCD
9.2
∴ BCX = DXC = 90°
( BC // XD)
()



3B_Ch9(*)
ABCD AD = 3 cm, DC = 5 cm, AE = 2 cm
9.2
(a) DAC,
9.2

DE
9.2
//
4a + 200° = 360°
()



3B_Ch9(*)
ABCD E F AC AE = FC DEBF
9.2
∴ AG – AE = GC – FC
y = 30°



3B_Ch9(*)
13 cm ABCD BD 10 cm
9.3
DE = EB
9.3

3B_Ch9(*)
ABCD AC DB E AB = 8 BC = 6 EB
9.3
3B_Ch9(*)
ABCD PCDB ABP AD = 8 cm ∠ADP = 72°
9.3
∴ BAD = BPD
( )

3B_Ch9(*)
PQRS PR QS T PT = 1
9.3
3B_Ch9(*)
ABCD E BC AC = EC ∠DAE
9.3
3B_Ch9(*)
ABCD O BD AC PQ O PO = QO

3B_Ch9(*)
ABCD P Q AB DC AP = QC PQ BD



3B_Ch9(*)
ABCD AFD CEB AF CE EF
(a)
(b) BD CF = 5 cm EF = 8 cm




ABC, AM = MB AN = NC MN // BC MN = BC

9.5
(ST // QR)
3B_Ch9(*)
AD = DB AE = EC DE = 3 cm∠DAE = 48° ∠ACB = 56°
(a) x y
()
3B_Ch9(*)
G F C BA BE BD AFC ∠BDE = 80° ED = 4 cm AF = 2 cm
(a) FC
3B_Ch9(*)
P Q R S ABCD AB BC CD DA PQRS

//
9.5.1


AN = NC.
DE = EF.
= 4
= 5
3B_Ch9(*)
AB // CD // EF AC = CE BD = 10 cm GD = 6 cm BH ⊥ EF
(a) DF (b) GH (c) HF
(a) AB // CD // EF and AC = CE
()
∴ GH = BG
3B_Ch9(*)
ADF AB = BC = CD AE = EF BE DF G
(a) DF = FG
(b) BE : EG