You can calculate the perpendicular distance the line is away from the circle centre, or given centreline,
using the area of the triangle.
$\displaystyle \displaystyle\frac{1}{2}r^2Sinx=\frac{1}{2}(2)rhSi n\left(\frac{x}{2}\right)=hrSin\left(\frac{x}{2}\r ight)$
$\displaystyle \displaystyle\Rightarrow\ h=\frac{1}{2}r\left[\frac{Sinx}{Sin\left(\frac{x}{2}\right)}\right]$
which you can then calculate, once you have the radius, since you now know x.
However, you only need the angle x or y to actually construct the diagram,
but if you want to calculate the distance between the centreline and your line of interest,
you can use the above equation for "h".
orginally posted by yeah
Reference your original drawing
Mark midpoint of diameter O. Draw a vertical line thru O meeting circle @ A Draw a horizontal I 60 %above A Intersection ofhorizontal and OA mark B Ends of horizontal meet circle @ C and D.
OA = 0.5 d. OB =0,2 d BA = 0.3d
Angle theta referred to by pickslides is determined by cosine property.
cosine theta = 0.2d/0.3d theta = 66.42 degrees. You can now calculate the area above and below CD. Answer will be close to exact value but you must set up a spreadsheet and calculate with lower values of theta until you zero in on the exact value. This method is simple trig and needs no proof. I omit the steps you should know to proceed from theta
bjh