Diameter? This segment connecting two points of the circle and passing through its center. Also referred to as the diameter of the length of the segment.
Consider several ways to calculate the diameter of the circle according to the input data.
Diameter (D) equal to the largest two radii (R):
D = 2 * R
If we know the circumference (L), then:
L = 2 * pi * the R
D = L / P
If you know the area of a circle (S), then:
S = P * R ^ 2
D = 2 * v (S / P)
In a Cartesian coordinate system:
the general equation of a circle centered at the origin:
x ^ 2 + y ^ 2 = R ^ 2, here
D = 2 * v (x ^ 2 + y ^ 2)
If both ends of known coordinates diameter (x1, y1) and (x2, y2):
D = v ((x1-x2) ^ 2 + (y1-y2) ^ 2)
In the case of the circle described about the triangle:
a / sin (alpha) = b / sin (beta) = c / sin (gamma) = 2R = D,
where a, b, c? sides of the triangle, as the alpha, beta and gamma? their opposing corners.
Formula for inscribed (r) and described radii (R) of the circles of the triangle:
R = a * b * c / (4 * S)
r = 2 * S / (a + b + c),
where a, b, c? sides of the triangle, S - its area.