Respuesta :

Answer:1385.44mm sq

Step-by-step explanation: surface area of a circle = pi x radius squared

3.142 x 21 squared

Answer:

Step-by-step explanation:

diameter = 42 mm

radius (r) = 42/2 = 21mm

SA of semicircle = 3πr²

[tex]=3*\frac{22}{7}*21*21\\\\=3*22*3*21\\\\=4158mm^{2}[/tex]

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