Math 122 – Trigonometry
Section [3.5] Video Worksheet – 9th Edition
Name__________________
Sum and Difference Formulas
Complete the equations
cos(   ) 
sin(   ) 
sin(  (  )) 
sin(   ) 
tan(   ) 
tan(  (  )) 
cos(  (  )) 
cos(   ) 
Find the exact value
5𝜋
7𝜋

sin ( 12 )

tan ( 12 )

cos(165°)

sin(105°)

sec (− 12)

cot (− 12 )

sin 20° cos 80° − cos 20° sin 80°

cos 40° cos 10° + sin 40° sin 10°

tan 20  tan 25
1  tan 20 tan 25

cos ( ) cos ( ) − sin ( ) sin ( )

𝜋
7𝜋
sin (12) cos ( 12 )

sin (18) cos ( 18 ) + cos (18) sin ( 18 )
𝜋
𝜋
7𝜋
− cos (12) sin ( 12 )
Find exact value under each condition
a. sin(a+b)
b. cos(a+b)
c. sin(a-b)

cos 𝑎 =
√5
,0
5
𝜋
4
5𝜋
5𝜋
12
7𝜋
12
5𝜋
12
7𝜋
12
𝜋
5𝜋
𝜋
5𝜋
d. cos(a-b)
𝜋
< 𝑎 < 2 ; sin 𝑏 = − 5 , − 2 < 𝑏 < 0

5
tan 𝑎 = 12 , 𝜋 < 𝑎 <
3𝜋
; sin 𝑏
2
1
= −2, 𝜋 < 𝑏 <
3𝜋
2