中一數學題,,,唔該,,,10分啊...

1.
(a)
triangle PQR ~ triangle TSR (given)
PQ/TS = QR/SR (corresponding sides, ~ triangles)
8 cm/6 cm = QR/7.5 cm
QR = 10 cm

(b)
triangle PQR ~ triangle TSR (given)
PQ/TS = PR/RT (corresponding sides, ~ triangles)
8 cm/6 cm = 6 cm/RT
RT = 4.5 cm

2.
triangle ABC ~ triangle DAC (given)
AB/DA = BC/AC = AC/DC (corresponding sides, ~ triangles)
AB/2 cm = 6 cm/4 cm = 4 cm/DC

(a) AB/2 cm = 6 cm/4 cm
AB = 3 cm

(b) 6 cm/4 cm = 4 cm/DC
DC = 8cm/3

(c) BD = BC - DC = 6 cm - 8cm/3 = 10 cm/3

[因為是中一數學題，我猜你不會找angle BAD，而BA和AD已知道，所以，我估你是想求BD。希望沒有猜錯吧！]

2007-03-04 22:35:45 補充：
以上提供的2(c)答案，是假設了D，這一點在BC這一條線上。如果D點在AB這一條線上的話，2(a)和2(b)仍是不變，但(c)的答案如下：BD = AB - AD = 3 cm - 2 cm = 1 cm希望我猜對這一題的圖啦！

2007-03-04 22:42:10 補充：
如你想想，D點是在BC或AB上，便有此可能。我的數學只是普普通通，哪有能力用vector或去找角度的大小？

我諗你問o既係三角形

1.PQR~TSR

TS/PQ=RS/RQ=RT/RP

a) 6/8=7.5/RQ
RQ=10

b) TS/PQ=RT/RP
6/8=RT/6
RT=4.5


2.ABC~DAC

AB/DA=BC/AC=AC/DC

a) AC/BC=DA/AB
4/6=2/AB
AB=3

b) AC/BC=DC/AC
4/6=DC/4
DC=2.67

c) 冇圖答你唔到
SORRY