If a pebble is dropped into a pond in the shape of an ellipse at the location of one focus, the waves will converge at the location of the other focus. If the pond has a major axis of 20 feet and a minor axis of 16 feet, how far apart are the foci?

12 feet
24 feet
36 feet
6 feet

Question

If a pebble is dropped into a pond in the shape of an ellipse at the location of one focus, the waves will converge at the location of the other focus. If the pond has a major axis of 20 feet and a minor axis of 16 feet, how far apart are the foci?

12 feet
24 feet
36 feet
6 feet

anonymous · Answer

@RadEn

anonymous · Answer

@amistre64 @mlamott15

anonymous · Answer

Sorry, I was away from my computer for a minute.

anonymous · Answer

i have no idea......what class is this from??

anonymous · Answer

Algebra 2. I'm stumped!

anonymous · Answer

@javikun1

amistre64 · Answer

they are c+c apart of course ....

amistre64 · Answer

|dw:1400688123273:dw|

anonymous · Answer

Would it be 36?

amistre64 · Answer

since a is half the width; and b is half the height ... pythag for c and solve

anonymous · Answer

a = 20/2 = 10 b = 16/2 = 8 a^2 - b^2 = 10^2 - 8^2 = 100 - 64 = 36 sqrt(a^2-b^2) = sqrt(36) = 6 2*6 = X

amistre64 · Answer

it has to be less than the width .... since 36 < 20 is simply absurd, then it aint 36

anonymous · Answer

6*2=X

anonymous · Answer

what is 6*2?

anonymous · Answer

I did 20^2+16^2=25.6. I don't know what I did wrong but your work makes sense to me now @Mason_Jones573

amistre64 · Answer

you didnt half them ... and you added the results instead of working the pythag

anonymous · Answer

Yep^

anonymous · Answer

Oh okay, I just reworked it and got the right answer. Thank you!