函数y=12sin(2x+π6)+5sin(π3-2x)的最大值为( ) A.6+532 B.17 C.13 D.12
问题描述:
函数y=12sin(2x+
)+5sin(π 6
-2x)的最大值为( )π 3
A. 6+
5
3
2
B. 17
C. 13
D. 12
答
y=12sin(2x+
)+5sin(π 6
-2x)=12sin(2x+π 3
)+5sin(π 6
-π 2
-2x)π 6
=12sin(2x+
)+5cos(2x+π 6
)π 6
=13[
sin(2x+12 13
)+π 6
cos(2x+5 13
)]π 6
=13sin(2x+
+φ)(φ为辅助角)π 6
则当2x+
+φ=2kπ+π 6
,k为整数,y取最大值13.π 2
故选C.