Eight coins fit exactly on a rectangular sheet of paper when lined up in 4 columns and two rows. each coin is in the shape of a regular dodecagon, a polygon containing 12 sides. what fraction of the paper sheet will not be covered?

≅0.034

Step-by-step explanation:

The graph shows a rectangle and 8 dodecahedrons but a dodecahedron inscribed in a square is seen, so it is enough to calculate the fractions of areas between the square and the dodecahedron

Square area

Area of a right triangle  

Area fraction

≅0.034

Note: The fractions of the sides of the square and the right triangle are determined by assigning values to L

addition

step-by-step explanation:

see explanation

step-by-step explanation:

a

(6r + 7) + (13 + 7r) ( remove brackets and collect like terms )

= 6r + 7 + 13 + 7r

= 13r + 20

b

remove brackets and collect like terms

13 - r - 1 + r

= 12 - r

c

remove brackets and collect like terms

= - 8 - r + 2r - 4

= - 12 + r

d

remove brackets and collect like terms

= 7r - - - 6r

[-   - = - - = - ]

= r -