Taylor Series Expansion of Sin(x) -- VBA -- Type Mismatch error

I'm new to VBA and am trying to make a program to solve the Taylor Series Expansion of Sin(x).

There is a '<Type Mismatch>' error on the line:
"deriv = ((h ^ i) * PLUSorMINUS * EVENorODD) / (Fact(i))"

It says "Fact(i)" is the problem. Any help would be appreciated.

Sub fsolver()

xLOW = 0.01
xHIGH = 1
imax = 100
Es = 0.0005

x = 0
h = x
i = 1
Ea = 0.01

EVENorODD = Cos(x)
deriv = 0
fSIN = 0
PLUSorMINUS = 1


Fact = Application.WorksheetFunction.Fact(i)

isEven = Application.WorksheetFunction.isEven(i)


Do
xOLD = x
x = (xLOW + xHIGH) / 2
h = x
If Ea <> 0 Then
    Ea = Abs((x - xOLD) / (x)) * 100
End If

deriv = ((h ^ i) * PLUSorMINUS * EVENorODD) / (Fact(i))
fSIN = Sin(x) + deriv


fLOW = fSIN(xLOW)
fHIGH = fSIN(xHIGH)

ABOVEorBELOW = fLOW * fHIGH

If ABOVEorBELOW < 0 Then
    xHIGH = x
    Else
    If ABOVEorBELOW > 0 Then
    xLOW = x
    End If
End If

Cells(1, 5) = "x"
Cells(i + 1, 5) = x
Cells(1, 6) = "Ea"
Cells(i + 1, 6) = Ea
Cells(1, 3) = "Result"      'fSIN value
Cells(i + 1, 3) = fSIN
Cells(1, 4) = "fLOW*fHIGH above or below 0"
Cells(i + 1, 4) = ABOVEorBELOW
Cells(1, 2) = "Truncated value"     'deriv value
Cells(i + 1, 2) = deriv
Cells(1, 1) = "i"
Cells(1 + i, 1) = i

i = i + 1

If isEven(i) = True Then
    EVENorODD = Sin(x)
    Else: EVENorODD = Cos(x)
End If


If i = [1,4,5,8,9] = True Then
    PLUSorMINUS = (1)
    Else: PLUSorMINUS = (-1)
End If


If Es > Ea Or i > imax Then Exit Do

Loop


End Sub