Question

Find the equation of the sphere if one of its diameters has endpoints (-7, -4, -8) and (-4, 2, 1).

Answer 1

this is what i've done. i found the distance, divided by 2 to get radius. then i found the center by saying the point halfway between the x, y, and z points. plugged my equation in and webwork says it's wrong. did i mess up somewhere in my algebra or what?

Answer 2

Find the center of the sphere by using the 3D midpoint formula\[\left(\frac{x_1+x_2}{2},\frac{y_1+y_2}{2},\frac{z_1+z_2}{2}\right).\]

Answer 3

Sorry, I didn't see you posted your work. I'll review it.

Answer 4

yeah, i did that. just got the math wrong on the last one, but the answer is still wrong somewhere

Answer 5

The \(z\) coordinate of your center is \(-5\). Why?

Answer 6

cause i goofed. i tried inputing this instead.

(x+5.5)^2+(y+1)^2+(z+3.5)^2-(sqrt(145)/2)^2

still wrong.

Answer 7

That is strange. I got: \((x+5.5)^2+(y+1)^2+(z+3.5)^2=145/4\).

Answer 8

weird. ok. i'll have to send this to my teacher then and ask wtf....thanks across.

Answer 9

Wait a moment.

Answer 10

ok

Answer 11

I took your measurement of distance to arrive at my conclusion, but just realized you said that \(9^2=100\).

Answer 12

oops....i did that the other day too. said 3+3=9....grr.....thanks!

Answer 13

You are welcome. Let me know if the answer passes.

Answer 14

webwork says :"The answer above is correct."................thanks!