Respuesta :

In cylindrical coordinates, we take

x = r cos(t)

y = r sin(t)

z = z

(a) Then

6x + 5y + z = 6

transforms to

6r cos(t) + 5r sin(t) + z = 6

(b) We have

x² + y² = r² (cos²(t) + sin²(t)) = r²

so

-4x² - 4y² + z² = 5

converts to

-4r² + z² = 5