Question 769706
Consider a right angled triangle.
The radius (half the diameter = 45ins)
is the hypotenuse.
And half of the chord is the base of
the right angled triangle = 27ins.
The distance from the centre is
represented by the vertical side 
of the triangle
Vertical side^2 + Base side^2 = Radius^2
Vertical side^2 = Radius^2 - Base side^2
Vertical side^2 = 45^2 - 27^2
Vertical side^2 = 1296
Vertical side = {{{sqrt(1296)}}}
Distance chord and centre = 36ins
Hope this helps.
:-)