Apps. and Interpretation for IBDP Maths Ebook 1 | Page 148

Your Practice Set – Applications and Interpretation for IBDP Mathematics
39
Paper 1 – Trigonometric Equations
Example
Consider the trigonometric function f ( x) �2cos x � 1, where �360 � x � 360 .
(a) Write down the period of the function f( x ).
(b) Find the maximum value of the function f( x ).
(c) Solve the equation f( x) �� 1.
[1]
[2]
[3]
Solution
(a) 360 A1 N1
(b)
The maximum value
�2(1) � 1
(M1) for valid approach
� 3
A1 N2
(c) f( x) �� 1
2cos x �1� � 1
2cos x �2 � 0
x �� 180 or x � 180
A2 N3
(M1) for setting equation
[1]
[2]
[3]
Exercise 39
1. Consider the trigonometric function f ( x) �sin 2x
� 1, where 0 �x
� 360 .
(a) Find the period of the function f( x ).
(b) Find the minimum value of the function f( x ).
(c) Solve the equation f( x) � 0 .
[2]
[2]
[2]
138
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