Analysis and Approaches for IBDP Maths Ebook 2 | Page 78

Your Practice Set – Analysis and Approaches for IBDP Mathematics
25
Paper 2 Section A – Graphs of Trigonometric Functions
Example
The function f is defined as f ( x) � Asec
Bx � C , x � 0 , A , B , C � . The coordinates
of the first local maximum and the first local minimum of the graph of f are (1,1) and
(2, 5) respectively.
(a) Find the values of A , B and C .
(b) Write down the range of f .
[4]
[1]
Solution
(a)
2� � 2(2 � 1)
B
2� � 2
B
B � �
A1
1� Asec�
� C
1� �A�
C
C�
A�
1
5 � Asec2�
� C
�5� A� A� 1
(M1) for substitution
4�
2A
A � 2
A1
C �2�
1
C � 3
A1
(b) { y : y �1 or y � 5}
A1
[4]
[1]
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