Cos(θ) = -20/√((-20)^2 +(-21)^2)
.. = -20/-√841 . . . . . . . . . . . . . . . . . θ is a 4th-quadrant angle, so cos(θ) > 0
.. = 20/29
The value of the cosine is 20/29.
The 3 panes would cost $7.65.
Max will be missing $1.78 in his account. Is that one of the fee choices?
