earth

Ausdruck 8: 0.7 4 times StartFraction, left parenthesis, "D" Subscript, "h" "o" "l" "l" "o" "w" , Baseline minus 2 "T" , right parenthesis cubed Over "D" cubed , EndFraction

equals

1568.0 3 2 9 2 2 1

Size comparison of solid and hollow discs (scroll out to see)

Ausdruck 10: "D" Subscript, "d" "o" "n" "u" "t" , Baseline equals StartFraction, "D" squared plus 4 "T" squared Over 4 "T" , EndFraction

equals

1960208

Ausdruck 11: "r" equals StartFraction, "D" Subscript, "d" "o" "n" "u" "t" , Baseline Over 2 , EndFraction minus left bracket, 0 , "T" , right bracket

Definitionsbereich \theta Minimum:

less than or equal to theta less than or equal to

2 pi

Definitionsbereich \theta Maximum:

equals

980104

980096

You could fit around these many solid discs inside the donut

Ausdruck 13: StartFraction, pi Over 2 StartRoot, 3 , EndRoot , EndFraction times StartFraction, left parenthesis, "D" Subscript, "d" "o" "n" "u" "t" , Baseline minus 2 "T" , right parenthesis squared Over "D" squared , EndFraction

equals

55552.8 2 0 2 0 3 8

Ausdruck 15: "r" less than or equal to StartFraction, "D" Over 2 , EndFraction

Definitionsbereich \theta Minimum:

less than or equal to theta less than or equal to

12 pi

Definitionsbereich \theta Maximum: