En la primera imagen.
Sacamos el Área de todo el circulo.
AreaCirculo = <img src="https://tex.z-dn.net/?f=%20%5Cpi%20%20r%20%5E%7B2%7D" />
El radio es 10 ya que va del centro rombo
AreaCirculo = <img src="https://tex.z-dn.net/?f=%20%5Cpi%2010%20%5E%7B2%7D%3D100%20%5Cpi" />
Ahora sacamos el area del rombo
AreaRombo = <img src="https://tex.z-dn.net/?f=%20%5Cfrac%7BDiagonalMayor%2ADiagonalMenor%7D%7B2%7D%20" />
AreaRombo = <img src="https://tex.z-dn.net/?f=%20%5Cfrac%7B6%2C6%2A10%7D%7B2%7D%20" />
AreaRombo = 33
ÁREA SOMBREADA
AreaSombreada = AreaCirculo - AreaRombo
AreaSombreada = <img src="https://tex.z-dn.net/?f=%20100%20%5Cpi%20-%2033" />
AreaSombreada = <img src="https://tex.z-dn.net/?f=%20281%2C16" />
La Cuarta Imagen RECTANGULO
AreaRombo = <img src="https://tex.z-dn.net/?f=L%2AL%20" />
AreaRombo = <img src="https://tex.z-dn.net/?f=2%2A8%3D16" />
AreaSemiCirculo = <img src="https://tex.z-dn.net/?f=%20%5Cfrac%7B%20%20%5Cpi%20r%5E%7B2%7D%20%7D%7B2%7D" />
AreaSemiCirculo = <img src="https://tex.z-dn.net/?f=%20%5Cfrac%7B%20%5Cpi%201%5E%7B2%7D%20%7D%7B2%7D" /> = [img = 10]
Lo multiplicamos por 4 semicirculos
[img = 11] = 2 [img = 12]
AreaSombreada = AreaRectangulo - Area4Semicirculos
AreaSombreada = 16 - 2[img = 13] = 9, 72.