gaokao 2019 Q12

gaokao · China · national-III-science_gkztc Trig Graphs & Exact Values
12. Let $f ( x ) = \sin \left( \omega x + \frac { \pi } { 5 } \right) ( \omega > 0 )$ . Given that $f ( x )$ has exactly 5 zeros on $[ 0,2 \pi ]$ , consider the following four conclusions:
(1) $f ( x )$ has exactly 3 local maximum points on $( 0,2 \pi )$
(2) $f ( x )$ has exactly 2 local minimum points on $( 0,2 \pi )$
(3) $f ( x )$ is monotonically increasing on $\left( 0 , \frac { \pi } { 10 } \right)$
(4) The range of $\omega$ is $\left[ \frac { 12 } { 5 } , \frac { 29 } { 10 } \right)$ The numbers of all correct conclusions are
A. (1)(4)
B. (2)(3)
C. (1)(2)(3)
D. (1)(3)(4)
II. Fill-in-the-Blank Questions: This section has 4 questions, each worth 5 points, for a total of 20 points.
D
12. Let $f ( x ) = \sin \left( \omega x + \frac { \pi } { 5 } \right) ( \omega > 0 )$ . Given that $f ( x )$ has exactly 5 zeros on $[ 0,2 \pi ]$ , consider the following four conclusions:\\
(1) $f ( x )$ has exactly 3 local maximum points on $( 0,2 \pi )$\\
(2) $f ( x )$ has exactly 2 local minimum points on $( 0,2 \pi )$\\
(3) $f ( x )$ is monotonically increasing on $\left( 0 , \frac { \pi } { 10 } \right)$\\
(4) The range of $\omega$ is $\left[ \frac { 12 } { 5 } , \frac { 29 } { 10 } \right)$\\
The numbers of all correct conclusions are\\
A. (1)(4)\\
B. (2)(3)\\
C. (1)(2)(3)\\
D. (1)(3)(4)

II. Fill-in-the-Blank Questions: This section has 4 questions, each worth 5 points, for a total of 20 points.\\