Respuesta :

38: it's a right triangle
39:
area:
[tex]a = \pi {r}^{2} [/tex]
[tex]a = 3.14 \times {10}^{2} = 314[/tex]

circumference:
[tex]c = \pi \times diameter[/tex]
[tex]c = 3.14 \times 20 = 62.8[/tex]