How fast is the top of the ladder falling right ...

NOW?!

The base of a 10 foot ladder is moving away from a wall at a speed of 1 foot per second.  

How fast is the top of the ladder traveling when the base is 6 feet from the wall?

t = 2.19 (slider from 0 to 10, step 0.0020)
A: (t, 0)
B: (0, (100 - MeanX[{A}]^(2))^(0.5))
a = Segment(B, A)
b = OrthogonalLine(B, a)
c = Circle(B, 0.5)
C = Intersect(c, b, 2)
d = OrthogonalLine(A, a)
e = Circle(A, 0.5)
D = Intersect(e, d, 2)
f = Segment(C, D)
E = Point(a)
F = Point(f)
G = Point(a)
H = Point(f)
I = Point(a)
J = Point(f)
K = Point(a)
L = Point(f)
M = Point(a)
N = Point(f)
O = Point(a)
P = Point(f)
Q = Point(a)
R = Point(f)
S = Point(a)
T = Point(f)
U = Point(a)
V = Point(f)
W = Point(a)
Z = Point(f)
A_1 = Point(a)
B_1 = Point(f)
C_1 = Point(a)
D_1 = Point(f)
E_1 = Point(a)
F_1 = Point(f)
G_1 = Point(a)
H_1 = Point(f)
g = Segment(E, F)
h = Segment(G, H)
i = Segment(I, J)
j = Segment(K, L)
k = Segment(M, N)
l = Segment(O, P)
m = Segment(Q, R)
n = Segment(S, T)
p = Segment(U, V)
q = Segment(W, Z)
r = Segment(A_1, B_1)
s = Segment(C_1, D_1)
a_1 = Segment(E_1, F_1)
b_1 = Segment(G_1, H_1)
I_1 = Intersect(xAxis, yAxis)
J_1 = (4.08, 2.22)
K_1 = (10.14, 4.94)
L_1 = (0.16, 8)