7) - 1
tan <BAD = BD / AD
BC = √(64 + 36)
BC = √100
BC = 10
now you can solve BD
BD/6 = 6/10
BD = 6*6 / 10
BD = 36/10
BD = 3.6
AD = √36 - 12.96
AD = √23.04
AD = 4.8
tan <BAD = BD / AD
tan <BAD = 3.6 / 4.8
tan <BAD = 0.75
7) - 2
cos <DAC + cos <DAB
as you know cos = Adj / Hypo
cos <DAC = AD/AC
cos <DAC = 4.8 / 8
cos <DAC = 0.6
cos <DAB = AD / AB
cos <DAB = 4.8/6
cos <DAB = 0.8
so
cos <DAC + cos <DAB = 0.6 + 0.8
cos <DAC + cos <DAB = 1.4
hope it helps