Periphery or Circumference. p = π d = 3.14d.

P = 2π r = 6.28r.

p = 2 √ π a = 3.54 √ a.

p = 2a / r = 4a / d.

Diameter and Radius, d = p / π = p / 3.14 r = p / 2π = p / 6.28.

d = 2√ a / π = 1.128 √ a r =√ a / π = 0.564 √ a.

Area of the Circle.

a = π d2 / 4 = 0.785d2 a = π r2 = 3.14r2

π = 3.14159265358979323846264338327950288 4197169399

2s = 6.283185 3π = 9.424778 4π= 12.566370 5π =15.707963 6π = 18.849556 7π = 21.991148 8π = 25.132741 9π = 28.274334 ¼π = 0.785398 ⅓π = 1.047197 ½π = 1.570796 ⅛π = 0.392699 1/6π = 0.523599 1/12π = 0.261799 2/3π = 2.094394 1/360π = 0.008726

1 / π = 0.318310

2 / π = 0.636619

3 / π = 0.954929

4 / π =1.273239

6 / π =1.909859

8 / π =2.546478

12 / π = 3.819718

360 / π = 114.5915

π2 = 9.869650

√π = 1.772453

√ 1 / π = 0.564189

√ π / 2 = 1.253314

√ 2 / π = 0.797884

Log. π = 0.49714987

61.

The periphery of a Circle is commonly expressed by the Greek letter π = 3.14 when the diameter d = 1 or the unit. For any other value of the diameter d, we will denote the periphery by the letter p, r = radius, and a = area of the circle. The periphery of a circle is equal to 3 14-100 times its diameter. c = chord.

62.

b = πrv /180 = 0.0175rv, v = 180b / πr = 57.296 b/r.

63.

w = 180 - v / 2, v = 2(180° - w).

64.

r = c2 + 4h2 / 8h = e2 / 2h,

65.

66.

67.

v = v, w = w, w + v = 180°, w > v.

68.

D = B + C, A' + B' + C = 180°,

B = D - C, A + B + C = 180°,

A'=A, B' = B.

69.

A + B + C = 180°,

A' = A, B' = B.

70.

E + C = A+D = 180°,

D = B + c,

E = A + B.

71.

(a + b)2 = a2 + 2ab + b2.

72.

(a - b)2 = a2 - 2ab + b2.

73.

(a + b) (a - b)= a2 - b2.

74.

a : b = c : d, ad = bc,

A = B.

75.

a : b = c : d, ad = bc.

76.

a : c = c : b, ab = c2 c = √ ab.

77.

A : B = a : b.

78.

a : x = x : a - x,

79.

c2 = a2 + b2, b2 = c2 - a2

80.

b2 = a2 + b2 - 2bd,

81.

C2 = a2 + b2 + 2bd,

82.

a : b = h : c, h = ac / b = ad / c , d = c2 / b = ch / a. 83.

a : c = d : (b - d), d = ab / c + a , v = v.

84.

a : c = b : d, ad = bc.

85.

a : t = t : b, t2 = ab.

86.

t2 = (a + b) (a - b),

87.

x = aR / R-r,

sin.v = t / a.

88.

89.

l = 2r - V,

r = ½ (l + V).

90.

91.

To find the length of a Spiral.

l = πrn = πr2 / P, n = 1 / πr = r / P,

P = πr2 / l = r / n. P = Pitch.

92.

To find the length of a Spiral.

l = π n (R+r), l = π / P (R2 - r2).

93.

Periphery of an Ellipse.

94.

To construct a screw Helix.

95.

To square a Circumference.

R = 0.555355 d =1.1107 r = 0.7071 S.

S = 0.785398 d = 1.57079 r = 1.4142 R d = 1.27322 S = 1.79740 R = 2r.

96.

To square a Circleplane.

R = 0.626657 d = 1.253314 r = 0.7071 S

S = 0.886226 d = 1.77245 r = 1.4142 R d =1.12838 S = 1.5367 R= 2 r.