In the triangle below P and Q are points on OA and OB respectively such that OP:PA=3:2 and OQ:QB=1:2.AQ and PQ intersect at T. Given that OA=a and OB=b,

a) Express AQ and PQ in terms of a and b.
b)Taking BT=kBP and AT=hAQ where h and k are real numbers;
i)find two expressions for OT in terms of a and b
ii) Use the expressions in b(i) above to find the values of h and k
iii) Show that B,T and P are collinear

1 answer

a) Since OP:PA = 3:2, we can set OP = 3x and PA = 2x for some factor x.
Similarly, since OQ:QB = 1:2, we can set OQ = y and QB = 2y for some factor y.

Now, we want to express AQ and PQ in terms of a and b.
AQ = AP + PQ = 2x + PQ
PQ = TP - TQ
But since TP and TQ are triangles formed by similar triangles OPT and OQT respectively,
TP:TO = PT:OT => TP = (PT/OT) * TO
Similarly, TQ:TO = QT:OT => TQ = (QT/OT) * TO

Therefore, PQ = (PT/OT) * TO - (QT/OT) * TO = (PT - QT) * (TO/OT)
Now, since PT and QT are proportional to OP and OQ respectively,
PT = (3x/5) * TO and QT = (y/3) * TO

Substituting these values into PQ, we get:
PQ = ((3x/5) * TO - (y/3) * TO) * (TO/OT)
PQ = ((TO/OT) * (3x/5 - y/3)) * TO

Finally, AQ = 2x + PQ = 2x + ((TO/OT) * (3x/5 - y/3)) * TO

b) i) To find expressions for OT, we can use similar triangles OPT and OQT.
In triangle OPT, OT:TO = PT:OT => OT * OT = PT * TO
OT^2 = (3x/5) * TO * TO => OT = sqrt((3x/5) * TO * TO)

Similarly, in triangle OQT, OT:TO = QT:OT => OT^2 = QT * TO
=> OT = sqrt((y/3) * TO * TO)

ii) We are given BT = kBP and AT = hAQ.
Using similar triangles OPT and OBT, we can set:
BT/TO = BP/PT => k = BP/PT
=> BP = k * PT

Using similar triangles OQT and OAT, we can set:
AT/TO = AQ/QT => h = AQ/QT
=> AQ = h * QT

iii) Now, we need to show that B, T, and P are collinear.
To do that, we will show that BP:PT = BT:TO, which is a property of collinearity.

From the previous step, we have BP = k * PT and BT = k * BP, so BT = k^2 * PT.

Therefore, BP:PT = k:1 and BT:TO = k^2:1.
Since BP:PT = BT:TO, we can conclude that B, T, and P are collinear.