- #1

radius

- 10

- 0

D=distance to star

theta=angle

using the rule D=(d/2)/tan(theta/2)

when d = 300*10tothe6

and theta = 5*10tothe-5

what is the distance to the star in km and light years?

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- Thread starter radius
- Start date

- #1

radius

- 10

- 0

D=distance to star

theta=angle

using the rule D=(d/2)/tan(theta/2)

when d = 300*10tothe6

and theta = 5*10tothe-5

what is the distance to the star in km and light years?

- #2

Jess

- 27

- 0

Okay - assuming that you've given the units in kilometres and degrees...

To get the answers in km you should just be able to plug the numbers into a calculator.

To get the answer in light years you have to first calculate how far a light year is (in km, obviously).

Rather than me just giving you the answer, why don't you have a go, then we can see if our answers agree...

Jess

To get the answers in km you should just be able to plug the numbers into a calculator.

To get the answer in light years you have to first calculate how far a light year is (in km, obviously).

Rather than me just giving you the answer, why don't you have a go, then we can see if our answers agree...

Jess

Last edited:

- #3

radius

- 10

- 0

hi there thankyou for your interest in my posting jess

d is in km

theta is in degrees

d is in km

theta is in degrees

- #4

Jess

- 27

- 0

You'll be wanting to hit 'post reply' rather than 'new thread', then

Oooh look - we've been moved

Jess

Oooh look - we've been moved

Jess

Last edited:

- #5

quantumdude

Staff Emeritus

Science Advisor

Gold Member

- 5,575

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Originally posted by Jess

You'll be wanting to hit 'post reply' rather than 'new thread', then

Jess

Presto! The threads are merged.

- #6

radius

- 10

- 0

343774677078406.6587981892079753

So, is this answer the number of km?

what is this answer in exponential form? ie: 34 * 10tothepower13?

1 light year is 9.467*10tothepower12, so in light years i think the distance will be:

27 light years

Please let me know if i am right

- #7

Jess

- 27

- 0

34 x 10^13 km is correct as well.

If you take the speed of light to be 300,000 km/s, then a light year is 9.461 x 10^12 km - which looks roughly like what you put.

I get an answer of 36.3 l.y though - you might have typed a digit wrong somewhere, perhaps. Even a back-of-the-envelope type calculation gives an answer of at least 34, if you look closely.

Jess

- #8

radius

- 10

- 0

thankyou very much jess!

I need the help for some uni coursework.

p.s. I am from edinburgh too!

- #9

Jess

- 27

- 0

This isn't Astronomy 1Ah or 1Ch work, is it?

- #10

radius

- 10

- 0

My coursework is from "horizons of science 1".

this module is concerned with the big bang, black holes, telecommunications and cosmological phenomena

- #11

Jess

- 27

- 0

Good luck with the rest of your course...

Jess

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