Question

A sphere has center (0,0,0) and a radius of 5. Which of the following points lies on the sphere? Use the distance formula, but adjust it to be used for three variables instead of two.
a. (0,-3,4)
b. (5,5,-5)
c. (2,3,0)
d. (1,-1,3)

Answer 1

@phi

Answer 2

the distance formula between a point (x,y,z) [this is in 3-D] and the point (0,0,0)
is
\[ \sqrt{x^2+y^2+z^2}\]
I would test each of your choices.

Answer 3

I'm confused??

Answer 4

each of your choices is an (x,y,z) "triplet"
square each number in the triplet (i.e. multiply each number by itself)
then add up. then find the square root.
if you get 5, then you found the correct triplet (correct choice)

Answer 5

Is b the answer??

Answer 6

Why do you think b is the answer?

Answer 7

I squared it

Answer 8

@Bobo-i-bo am I right?

Answer 9

Please show your working so I can understand what you are doing! And no, you're not right :P

Answer 10

\[\sqrt(5^{2}+5^{2}-5^{2}) \]

Answer 11

@Bobo-i-bo that's what I did

Answer 12

Oh sorry, you are right >.<

Answer 13

Yes, you have right answer >.<

Answer 14

What did you think it was?

Answer 15

Oh no, you did it wrong, sorry you aren't right after all. Your working should be
\[\sqrt{5^2+5^2+(-5)^2}\]
but I thought you wrote
\[\sqrt{5^2+5^2-(5)^2}\]
which confused me. You're not right :P

Answer 16

You know that we want to find the option which would give us \(5=\sqrt{x^2+y^2+z^2}\) right?

Answer 17

OHHHH it's A!!!
Yeah I made a mistake I didn't put the -5 in Parentheses, I recalculated it the right way and got 8.66 something.

Answer 18

So it's A?? @Bobo-i-bo

Answer 19

yes :)

Answer 20

you understand why right?

Answer 21

@Bobo-i-bo
Can you help with one more?? Or do you mind?

Answer 22

do it in a new thing :)