maths help (1 Viewer)

[tacogym27101990]

Re: maths help needed ASAP

uhh sry but could u please explain how to get the domain. i seem to be lost

well i just made one up as you didnt tell us what it was
0=<x=<360 is just the most common way

but if your not given a domain you have to use the general solutions
so here goes:

tan(x-60)=-rt3
x-60= 180n - tan^-1x(-rt3), where n is some integer
x- 60 =180n - 60
x=180n

 

[tacogym27101990]

Re: maths help needed ASAP

S | A
-----------------
T | C

All Stations To Central

(anti-clockwise)
First domain, all angles produce positive results with cos, tan and sin.
Second domain only sin is positive, tan and cos is negative.

So on and so forth.

your thinking quadrants tommykins

 

[tommykins]

Re: maths help needed ASAP

your thinking quadrants tommykins

Yeah i didn't read her post

 

[tacogym27101990]

Re: maths help needed ASAP

Yeah i didn't read her post

lol i do that all the time

howd you go in ure maths trials??

 

[bubblesss]

Re: maths help needed ASAP

your thinking quadrants tommykins

actually i meant how u got the angles -60etc thanks in advanced

 

[squeenie]

Re: maths help needed ASAP

Have you done exact values in trig yet?

 

[tommykins]

Re: maths help needed ASAP

lol i do that all the time

howd you go in ure maths trials??

92/120, came top 8/35 in my grade.
Guy that came first got 110/120

 

[tacogym27101990]

Re: maths help needed ASAP

actually i meant how u got the angles -60etc thanks in advanced

well if you put tan^-1(-rt3) in your calculator you get -60
and then you get the other angles like tommykins said:
the angles are negative so you know tan is negative in the 2nd and 4th quadrants, so the angles are 180 -tan^-1rt and 360 - tan^-1rt3

 

[tacogym27101990]

Re: maths help needed ASAP

92/120, came top 8/35 in my grade.
Guy that came first got 110/120

oh right i got about the same 93/120, made so many stupid mistakes cause i was so tired, easily couldve gotten above 100 i reckon if i hadnt made them
how about in 3 unit?? i got 81/84. lost all my marks on stupid mistakes like writing the answer off my calculator wrong, so im kinda disappointed

 

[bubblesss]

Re: maths help needed ASAP

well if you put tan^-1(-rt3) in your calculator you get -60
and then you get the other angles like tommykins said:
the angles are negative so you know tan is negative in the 2nd and 4th quadrants, so the angles are 180 -tan^-1rt and 360 - tan^-1rt3

yep thnx i get it now!
and woot woot!!!!!!!!!!!!!!!!!! this is my 100TH post YAY!!!!!!!!!!

 

[tacogym27101990]

Re: maths help needed ASAP

yep thnx i get it now!
and woot woot!!!!!!!!!!!!!!!!!! this is my 100TH post YAY!!!!!!!!!!

thats good to hear
so are you learning this by yourself?

 

[bubblesss]

Re: maths help needed ASAP

thats good to hear
so are you learning this by yourself?

oh no we learnt this ages ago and my brain seems to have gone rusty. i just had some problems with the + and -
honestly u thoought i was learning it for the first time right? how embarrassing lol.

 

[tacogym27101990]

Re: maths help needed ASAP

oh no we learnt this ages ago and my brain seems to have gone rusty. i just had some problems with the + and -
honestly u thoought i was learning it for the first time right? how embarrassing lol.

well different schools learn topics at a different stages
like alot of people learn apps of calculus in yr 11 but it was the last yr 12 topic i learnt
so i just figured you mightve been learning it now.. sorry

 

[bubblesss]

Re: maths help needed ASAP

well different schools learn topics at a different stages
like alot of people learn apps of calculus in yr 11 but it was the last yr 12 topic i learnt
so i just figured you mightve been learning it now.. sorry

na na dont be sorry. its cool. ayway its my fault - not revising trig now and then.

 

[tommykins]

Re: maths help needed ASAP

oh right i got about the same 93/120, made so many stupid mistakes cause i was so tired, easily couldve gotten above 100 i reckon if i hadnt made them
how about in 3 unit?? i got 81/84. lost all my marks on stupid mistakes like writing the answer off my calculator wrong, so im kinda disappointed

Disappointing for 3unit, only got 67/84.

Was sick on the day and just choked miserably, despite my ranking being 20/87.

 

[tacogym27101990]

Re: maths help needed ASAP

wow 87 3 uniters
guess you go to a smart school then??
which test did you do??
i think i was doin the western region

do you reckon youd get a band 6 ( E4 or whatever its called)
for getting 100/120 in 4 unit??

by the way, hope your not too devd with your 3 unit mark??
cause im sure ure hsc mark will make up 4 it

 

[SeftonIsAHole]

Re: maths

trigonometry fundamental formulas (not sure if they're called this)

SIN
when sinx=sina
x = a + k360 or x = (180-a) +k360
where k is any integer

COS
when cosx=cosa
x = +-a +k360
where k is any integer

TAN
when tanx=tana
x = a + k180
where k is any integer

x is the angle/s that you are trying to find
and a is a value you obtain or given in the question..if that makes sense

These are derived from the unit circle.

 

[ratcher0071]

Re: maths

Depends on the domain given.

But let me assume that it is 0 <= x <= 360 so 0 <= 2x +60 <= 780

cos(2x+60) = 0.5
2x + 60 = 60, 300, 420, 660 and 780
2x = 0, 240, 360, 600 and 720
x = 0, 120, 180, 300 and 360

For the people who didn't know what lyounamu was doing, here is an explanation:

Line 1: The question
Line 2: Cos^-1 both sides to get solutions 60, 300, 420, 660, 780
Line 3: -60 to both sides
Line 4: Divide by 2 on both sides

 

[ratcher0071]

Re: maths help needed ASAP

solve x
tan (x-60)= - square root 3

thanks in advance.

Domain: 0 <= x <= 360

tan(x-60)= -sqrt 3
(x-60)= -60, 120, 300
x= 0, 180, 360

This question is explained below:
line 1: question
line 2: tan^-1 both sides to get -60, 120 and 300
line 3: +60 to both sides

 

[lyounamu]

Re: maths

For the people who didn't know what lyounamu was doing, here is an explanation:

Line 1: The question
Line 2: Cos^-1 both sides to get solutions 60, 300, 420, 660, 780
Line 3: -60 to both sides
Line 4: Divide by 2 on both sides

Step-by-step explanation. Awesome~~