a) Later
b) Since,
cosθ = -4/5, 90° ≤ θ ≤ 180°
base, b = -4
hypotenuse, h = 5
So perpendicular, p = 3 using pythagoras theorem
Therefore, sinθ = 3/5 => sin^2 θ = 9/25 --------------------(1)
Again, sin β = - 4/11, 270° ≤ β ≤ 360°
So, p = -4, h = 11
b = √{11^2 - (-4)^2} = √105
so, tanβ = -4/√105 => tan^2 β = 16/105 ------------------(2)
Using (1) and (2):
tan^2 β - sin^2 θ = 16/105 - 9/25 = -109/525