Apps. and Interpretation for IBDP Maths Ebook 1 | Page 115

(c) The gradient of L
2
4
� �1�
3
(d)
(e)
(f)
3
�� (A1) for correct value
4
The equation of L
2
:
3
y �� x
A1 N2
4
� 3 �
4x�3�� x�� 60 � 0
(M1) for substitution
� 4 �
6.25x �� 60
x �� 9.6
3
y � � ( � 9.6)
(M1) for substitution
4
y � 7.2
Thus, the coordinates of C are ( � 9.6, 7.2) . A1 N3
The area of the triangle OBC
(20 � 0)(0 � ( �9.6))
� (A1) for correct formula
2
� 96
A1 N2
2 2
BC � ( �9.6 � 0) � (7.2 � 20)
BC � 16
(A1) for correct value
2 2
OC � ( �9.6 � 0) � (7.2 � 0)
OC � 12
(A1) for correct value
The perimeter of the triangle OBC
�12 �16 � 20
(M1) for valid approach
� 48
A1 N4
[2]
[3]
[2]
[4]
10
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