of a sphere witha center (1,4,-3) and tangent to the xz plane

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- May 5th 2009, 12:27 PMtiga killawrite the equation
of a sphere witha center (1,4,-3) and tangent to the xz plane

- May 5th 2009, 01:34 PMskeeter
- May 5th 2009, 01:38 PMSoroban
Hello, tiga killa!

Quote:

Write the equaton of a sphere with center (1,4,-3) and tangent to the xz-plane

Can you visualize the sphere?

. . If it is tangent to the xz-plane, the radius is 4.

Therefore: .$\displaystyle (x-1)^2 + (y-4)^2 + (x+3)^2 \:=\:16$

- May 5th 2009, 01:43 PMInfophile
Hello,

You have just to find the radius of this sphere.

It corresponds of the abscissa since it has to be tangent to $\displaystyle (O_z)$.

Hence $\displaystyle \color{red}R=1$ and thus the equation of the sphere is $\displaystyle \color{red}(x-1)^2+(y-4)^2+(z+3)^2=1$

**Edit**: What I called $\displaystyle (O_z)$ is the plan $\displaystyle (Oyz)$, maybe the sphere is tangent to $\displaystyle (Oxz)$ ?

:)