jwb

tan(1/2x) = (1 - cos(x)) / sin(x) (tangen)

tan(1/2(a+b)) = 7 (persamaan)

(1 - cos(a+b)) / sin(a+b) = 7

tan(1/2(a-b)) = 3 (persamaan)

1 - cos(a-b)) / sin(a-b) = 3 (gabung sin(a+b) sm sin(a-b))

1 - cos(a)cos(b) - sin(a)sin(b)) / sin(a)cos(b) = 7

1 - cos(a)cos(b) + sin(a)sin(b)) / sin(a)cos(b) = 3

1 - cos(a)cos(b) - sin(a)sin(b) = 7sin(a)cos(b) (kali)

1 - cos(a)cos(b) + sin(a)sin(b) = 3sin(a)cos(b)

2sin(a)sin(b) = 7sin(a)cos(b) + 3sin(a)cos(b) (tambah persamaan utk ngilangin cos(a)cos(b))

2sin(a)sin(b) = 10sin(a)cos(b)

sin(a)sin(b) = 5sin(a)cos(b)

sin(b) = 5cos(b)

tan(b) = 5

tan b = 5