Question 1178372
For {{{s = 20}}}:

{{{A=(1/4)sqrt(5(5+2sqrt(5)))*s^2}}}

{{{A=(1/4)sqrt(47.3606797749979)*20^2}}}

{{{A=(1/4)*6.8819*400}}}

{{{A=6.8819*100}}}

{{{A=688.19cm^2}}}



The area of the {{{10 }}}cm :

{{{A=(1/4)sqrt(47.3606797749979)*10^2}}}

{{{A=(1/4)*6.8819*100}}}

{{{A=6.8819*25}}}

{{{A=172.05cm^2}}}



Area between : {{{688.19cm^2-172.05cm^2=516.14cm^2}}}