1. sin (a+b)
2. cos (a+b)
3. Tan(a-b)
Deketahui sin a = 0,6 dan sin b = 0,8. Jika a lancip b tumpultentukan
1. sin (a+b) = sin a cos b + cos a sin b cari cos b => sin²b + cos²b = 1
= 6/10 6/10 + 8/10 8/10 64/100 + cos²b = 1
= 36/100 + 64/100 cos²b = 36/100
= 100/100 = 1 cos b = 6/10
cari cos a => sin²a + cos²a = 1
36/100 + co²a = 1
cos²a = 64/100
cos a = 8/10
2. cos (a+b) = cos a cos b – sin a sin b
= 8/10 6/10 – 6/10 8/10
= 0
3. tan (a-b) = tan a – tan b = 6/8 – 8/6 = 6/8 -8/6 = 0
1 – tan a tan b 1- 6/8.8/6 0
tan a = 6/8
tan b = 8/6