Challenge Question

[dr nick]

This is not easy (you've been warned), and it's a question i made up to help with my goalkicking but am having trouble solving it.

Firstly, a bit of background:

In Rugby Union/League, if you score a try 15 metres to the right of the uprights, you are allowed to take a shot at goal on the line at which you scored the try (ie 15m to the right of the right goal post). You can take it 2 metres out from the try line if you want, but the angle will be very hard. You can also take it from 50 metres out, but as you go further back, the angle you have to work with also reduces because of the distance.

What i want to know is how far back you have to go in order to have the maximum angle with which to work with when shooting for goal. (the goalposts are 10 metres apart)

does anybody know how to do this?



ok, whew, i think i've worked it out actually, but i'll leave it up incase anybody else wants a crack

 

[DaveW]

Um, surely the further back you are the better the angle.

There is no "maximum" (should that be minimum?) angle. The further back you go the closer you get to no angle.

 

[dr nick]

Originally posted by DaveW
Um, surely the further back you are the better the angle.

There is no "maximum" angle. The further back you go the closer you get to no angle.

no, if you go a kilometre back, you will have a tiny angle to work with....

incase i didnt word the question very well, what you say is true if you are right in front of the uprights. if you are not directly in front, there is a maximum somewhere

 

[DaveW]

Originally posted by nicko18
no, if you go a kilometre back, you will have a tiny angle to work with....

Exactly.

 

[dr nick]

Originally posted by DaveW
Exactly.

ok i misread what you said. if you are kicking from the sideline 2 millimetres out from the try line, you will also have no angle

Originally posted by DaveW
Um, surely the further back you are the better the angle.

this is the line of yours which confused me

 

[DaveW]

Originally posted by nicko18
ok i misread what you said. if you are kicking from the sideline 2 millimetres out from the try line, you will also have no angle

Wouldn't that be a huge angle? ~90 degrees

 

[dr nick]

Originally posted by DaveW
Wouldn't that be a huge angle? ~90 degrees

i'm talking about the angle between the uprights from the kickers view (sorry). you know how if you take a kick from the sideline, you take it about 20 metres back so you can get a better angle at which to shoot at??

 

[DaveW]

Originally posted by nicko18
this is the line of yours which confused me

If you're 15m from goal and 15m back from the line, that's a 45 deg angle.

If you're 15m from goal and 30m back from the line, that's a 27 deg angle.

15m from goal and 45m back = 18 deg

The further back you go the more you decrease the angle.

 

[dr nick]

Originally posted by DaveW
If you're 15m from goal and 15m back from the line, that's a 45 deg angle.

you might have a 45 degree angle to the right goalpost, and a 35 degree angle to the left post (thus having a 10 degree angle to work with)

if only i could draw a picture

 

[DaveW]

Originally posted by nicko18
you might have a 45 degree angle to the right goalpost, and a 35 degree angle to the left post (thus having a 10 degree angle to work with)

if only i could draw a picture

Oh yeah I wasn't considering about the particulars of each post. Not that it really changes anything.

 

[dr nick]

Originally posted by DaveW
Not that it really changes anything.

it does, because if you are 2 millimetres out, you will have no angle, and if you are 1 km back, you will also have no angle, so there is a maximum in between (19.4 metres back if you are curious)

 

[DaveW]

Originally posted by nicko18
it does, because if you are 2 millimetres out, you will have no angle, and if you are 1 km back, you will also have no angle, so there is a maximum in between (19.4 metres back if you are curious)

If you're 1 km back you're almost straight in front.

I don't know how you came to that conclusion.

 

[DaveW]

Ohhh, I finally get it.

The difference in angles between the two posts.

Sorry.

 

[dr nick]

Originally posted by DaveW
If you're 1 km back you're almost straight in front.

I don't know how you came to that conclusion.

yes, you are almost straight in front, but the angle between the posts from your view is tiny.

read your pm's