Calculations with a circular layer or circular zone in a semicircle. A circular layer is the difference between two circular segments, it is made of two parallel chords in a circle, which are on the same side of the circle center (or s through the center, if i=0). Enter three of the four values of radius and h, i, j and choose the number of decimal places. Then click Calculate. Angles are calculated and displayed in degrees, here you can convert angle units.
r = h + i + j
s = 2 * √ 2 * r * (h+j) - (h+j)²
t = 2 * √ 2 * r * j - j²
Θs = 2 * arccos( 1 - (h+j) / r)
Θt = 2 * arccos( 1 - j / r)
l = r * ( Θs - Θt ) / 2
p = s + t + 2 * l
A = [ r² * ( Θs - Θt ) - s * i + t ( r - j ) ] / 2
Radius, height, distances, chords and perimeter have the same unit (e.g. meter), the area has this unit squared (e.g. square meter). For the angles Θ see circular segment.