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Exercicios resolvidos James Stewart vol. 2 7ª ed - ingles

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. . . y2 2<br />

33. An equivalent equation IS - x 2 + 4<br />

-;- z = 1, a 35. Completing the squate in y gives<br />

hyperboloid of two sheets with axis the y-ax.is. For<br />

IYI > 2, traces parallel to the xz-plane are circles.<br />

z<br />

CHAPTER 12 REVIEW 0 145<br />

z2<br />

4x 2 + 4(y - 1) 2 + z 2 = 4 or x 2 + (y - 1) 2 +- = 1,<br />

4 .<br />

an ellipsoid center<strong>ed</strong> at (0, 1, 0).<br />

(0, 1,2)<br />

(O, l ,-2)<br />

<br />

. x2 y2 2 2 2<br />

4 + 16 = l. The equation of the ellipsoid is ~ + i 6 + : 2<br />

= l, since the horizontal trace in the<br />

plane z = 0 must be the original ellipse. The traces of the ellipsoid in the yz -plane must be circles since the surface is obtain<strong>ed</strong><br />

2 2 2<br />

by rotation about the x-axis. Therefore, c 2 = 16 and the equation of the ellipsoid is ~ + i 6<br />

+ ~ 6<br />

= 1 <br />

4x 2 + y 2 + z 2 = 16.<br />

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