a) Diagonal Maior do losango: [tex3]D =20 - 2.1,7 = 16,6 [/tex3]
Diagonal Menor do losango: [tex3]D =14 - 2.1,7 = 10,6 [/tex3]
[tex3]S_{losango} = \frac{D.d}{2} = \frac{16,6.10,6}{2} = 87,98\\
S_ \bigcirc = \pi r^2 = 3,14.3,5^2 = 38,465\\
\therefore S_{amarela} = 87,98-38,465 = \boxed{49,515} [/tex3]...