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Help with Trig question (1 Viewer)

lovepink

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From the top of the vertical cliff 68m high, an observer notices a yacht at sea, The angle of depression to the yacht is 47 degrees. The yacht sails directly away from the cliff and after 10min the angle of depression is 15 degrees how fast is the yacht sailing?
 

HeroicPandas

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D = S x T

Distance = Speed x Time

T = 10 min = 10 x 60 = 600 seconds

Distance = Change in distance from first boat to second boat

I thought general math don't learn trigonometry

Say something, so i can decide the future
 
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lovepink

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what..i know that is not right :|
answer in the textbook says 1.14km/hr i just don't know how to work it out
 

HeroicPandas

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what..i know that is not right :|
answer in the textbook says 1.14km/hr i just don't know how to work it out
do u want me to scan my solution? (it'll be easy to see)

but u must promise me not to just skim through it and go "yes i see, i get the idea" then forget about it
 

lovepink

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um i wont ? i need to know, something like this might be in the trials/hsc exam
 

Makematics

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so is trig in general? shiet i underestimated the diffculty of general.
 

HeroicPandas

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you dont, but you tried your best :D if he/she doesnt understand, they can ask you for further help cant they?
a confirmation is all i need! (eg. i get it, me understand, etc)

even if i waste 2 hours of life writing up a solution to help a person, if he/she says "yes" i'll be happy
 
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Makematics

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a confirmation is all i need! (eg. i get it, me understand, etc)

even if i waste 2 hours of life writing up a solution to help a person, if he/she says "yes" i'll be happy
oh yeah i know what you mean. i get pissed off when people like you write up solutions and then the person doesn't even say thank you -.-
 

lovepink

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a confirmation is all i need! (eg. i get it, me understand, etc)

even if i waste 2 hours of life writing up a solution to help a person, if he/she says "yes" i'll be happy
hahaha woah wasted your time? you need to chill out im not on this website 24/7 okay so dont expect a reply straight away

and yes thankyou for taking your time and putting up the working out, i do appreciate it.
but you totally lost me with 'therefor y= 68- xtan15 over ..and the one below that, like please explain
 

Smile12345

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but you totally lost me with 'therefor y= 68- xtan15 over ..and the one below that, like please explain
I did it slightly different to this (and I still got the same answer!)....
I worked out what x was (63.41102586) and
then I worked out what x+y was (253.7794549)... Both using the Tan=Opposite/Adjacent as HeriocPandas did....
Then I got the difference between these two numbers.... (which is Y)
This was what was done in 10 minutes so multiply the number by 6 (to get 60mins/hr)... Don't forget your answer will be in metres...

Trust this helps... :) I'll be back in 5 mins....
 
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lovepink

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I did it slightly different to this (and I still got the same answer!)....
I worked out what x was (63.41102586) and
then I worked out what x+y was (253.7794549)... Both using the Tan=Opposite/Adjacent as HeriocPandas did....
Then I got the difference between these two numbers.... (which is Y)
This was what was done in 10 minutes so multiply the number by 6 (to get 60mins/hr)... Don't forget your answer will be in metres...

Trust this helps... :) I'll be back in 5 mins....
ah i get it!! thankyou so much x
 

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