Long Question 1


Question 1:


The above diagram shows triangle OAB. The straight line AP intersects the straight line OQ at R. It is given that OP= 1 4 OB, AQ= 1 4 AB,  OP =4 b ˜  and  OA =8 a ˜ .  

(a) Express in terms of   a ˜  and/ or  b ˜ :
( i ) A P (ii) O Q

(b)(i) Given that A R = h A P , state   A R  in terms of h   a ˜  and  b ˜ .
 (ii) Given that   R Q = k O Q , state  in terms of k,   a ˜  and  b ˜ .

(c) Using   A Q = A R + R Q ,   find the value of h and of k.

Solution
:

(a)(i)
A P = A O + O P A P = O A + O P A P = 8 a ˜ + 4 b ˜


(a)(ii)
O Q = O A + A Q O Q = 8 a ˜ + 1 4 A B O Q = 8 a ˜ + 1 4 ( A O + O B ) O Q = 8 a ˜ + 1 4 ( 8 a ˜ + 4 O P ) O Q = 8 a ˜ + 1 4 ( 8 a ˜ + 4 ( 4 b ˜ ) ) O Q = 8 a ˜ 2 a ˜ + 4 b ˜ O Q = 6 a ˜ + 4 b ˜


(b)(i)
A R = h A P A R = h ( 8 a ˜ + 4 b ˜ ) A R = 8 h a ˜ + 4 h b ˜


(b)(ii)
R Q = k O Q R Q = k ( 6 a ˜ + 4 b ˜ ) R Q = 6 k a ˜ + 4 k b ˜


(c)
A Q = A R + R Q A Q = 8 h a ˜ + 4 h b ˜ + ( 6 k a ˜ + 4 k b ˜ ) A O + O Q = 8 h a ˜ + 4 h b ˜ + 6 k a ˜ + 4 k b ˜ 8 a ˜ + 6 a ˜ + 4 b ˜ = 8 h a ˜ + 6 k a ˜ + 4 h b ˜ + 4 k b ˜ 2 a ˜ + 4 b ˜ = 8 h a ˜ + 6 k a ˜ + 4 h b ˜ + 4 k b ˜ 2 = 8 h + 6 k 1 = 4 h + 3 k ( 1 ) 4 = 4 h + 4 k 1 = h + k k = 1 h ( 2 ) Substitute (2) into (1), 1 = 4 h + 3 ( 1 h ) 1 = 4 h + 3 3 h 4 = 7 h h = 4 7 From (2), k = 1 4 7 = 3 7

Long Question 3


Question 3:
In diagram below, PQRS is a quadrilateral. PTS and TUR are straight lines.
 
 
It is given that PQ =20 x ˜ ,   PT =8 y ˜ ,   SR =25 x ˜ 24 y ˜ ,   PT = 1 4 PS   and   TU = 3 5 TR
(a) Express in terms of x ˜ and/or   y ˜ :
 (i)   Q S
 (ii) T R
(b) Show that  the points  Q, U and S  are collinear.
(c) If   | x ˜ | = 2  and | y ˜ | = 3, find   | Q S |


Solution:

(a)(i)
QS = QP + PS QS =20 x ˜ +32 y ˜ Given  PT = 1 4 PS PS =4 PT =4( 8 y ˜ )=32 y ˜


(a)(ii)
T R = T S + S R T R = 3 4 P S + 25 x ˜ 24 y ˜ T R = 3 4 ( 32 y ˜ ) + 25 x ˜ 24 y ˜ T R = 24 y ˜ + 25 x ˜ 24 y ˜ T R = 25 x ˜


(b)
QU = QP + PT + TU QU =20 x ˜ +8 y ˜ + 3 5 ( 25 x ˜ ) Given TU = 3 5 TR QU =20 x ˜ +8 y ˜ +15 x ˜ QU =5 x ˜ +8 y ˜ From (a)(i)  QS =20 x ˜ +32 y ˜ QS QU = 20 x ˜ +32 y ˜ 5 x ˜ +8 y ˜ QS QU = 4( 5 x ˜ +8 y ˜ ) ( 5 x ˜ +8 y ˜ ) QS QU =4 QS =4 QU  Q, U and S are collinear.


(c)









P S = 32 y ˜ | P S | = 32 | y ˜ | | P S | = 32 × 3 = 96 P Q = 20 x ˜ | P Q | = 20 | x ˜ | | P Q | = 20 × 2 = 40 | Q S | = 96 2 + 40 2 | Q S | = 104