C H A P T E R 5 Analytic Trigonometry

26.
27.
28.
29.
cot u 4, 3
2 < u < 2
1
sin 2u 2 sin u cos u 2 17 4 8
17 17
cos 2u cos 2 u sin 2 u
tan 2u
tan 2u
4
17 2 1
17 2
15
17
2 tan u
1 tan 2 u
2 tan u
1 tan 2 u
21
1 21
4
421
17
21 4
1 1 4
cos 2u cos2 u sin 2 u 2 5 2
2 21
2
2 8
15
sec u 5 21
, < u < ⇒ sin u
2 2 5
sin 2u 2 sin u cos u 2 21
5 2
1 21
2 2
cos 2u cos2 u sin2 22
u 3 2
1
tan 2u
2 tan u
1 tan 2 u
2 2
4
1 2
4
5 421
25
21
5 2
17
25
sin 2u 2 sin u cos u 2 1 22 42
3 3
9
cos4 x cos2 xcos2 1 cos 2x
x 2
2 42
7
Section 5.5 Multiple-Angle and Product-to-Sum Formulas 495
and cos u 2
5
3 2
7
9
1
3
− 2 2
1 cos 2x
2 1 2 cos 2x cos2 2x
4
1 2 cos 2x
4
3 4 cos 2x cos 4x
8
u
y
y
u
4
17
1 cos 4x
2
2 4 cos 2x 1 cos 4x
8
1
3 4 cos 2x cos 4x
8
x
−1
x