maths help (1 Viewer)

[marcquelle]

Re: maths

yep thats it

this is one of the few units that i fully understand.

 

[bubblesss]

Re: maths

can anyone please help me with this question aswell.
tan (2x - 45) +1 =0
domain is 0<=<=360
thanks in advanced.

 

[bubblesss]

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

thanks. this is one of my least favorite sections.

 

[lyounamu]

Re: maths

can anyone please help me with this question aswell.
tan (2x - 45) +1 =0
domain is 0<=<=360
thanks in advanced.

0<= x <= 360
so -45<= 2x-45 <= 675


tan (2x-45) = -1
(2x-45) = -45, 135, 315, 495, 675
2x = 0, 180, 360, 540 and 720
x = 0, 90, 180, 270 and 360.

 

[bubblesss]

Re: maths

0<= x <= 360
so -45<= 2x-45 <= 675


tan (2x-45) = -1
(2x-45) = -45, 135, 315, 495, 675
2x = 0, 180, 360, 540 and 720
x = 0, 90, 180, 270 and 360.

could u please tell me how u do that? ur method is way better than wat we learnt @ skool. is it the same case for all questions? thanks in advance.

 

[lyounamu]

Re: maths

could u please tell me how u do that? ur method is way better than wat we learnt @ skool. is it the same case for all questions? thanks in advance.

Ok, what I do is:

0 <= x <= 360
0 <= 2x <= 720
0 <= 2x-45 <=675

This method works for all types of questions related to this topic.

 

[bubblesss]

Re: maths

Ok, what I do is:

0 <= x <= 360
0 <= 2x <= 720
0 <= 2x-45 <=675

This method works for all types of questions related to this topic.

wasn't there a -45 instead of 0?

 

[marcquelle]

Re: maths

tan(180-45) = -1
therefore 135+135 = 270
therefore x = 0, 90, 180, 270 and 360.

(ignore my working out its just my quick method that i do in my mind)

 

[lyounamu]

Re: maths

wasn't there a -45 instead of 0?

Yep. I contradicted myself there, lol.

 

[tacogym27101990]

Re: maths

hey lyounamu have you decided whether your gunna do 4 unit or not yet???

 

[lyounamu]

Re: maths

hey lyounamu have you decided whether your gunna do 4 unit or not yet???

I think I will give a go. If I can pull off 48 or over in mx1, I will definitely do it.

 

[tacogym27101990]

Re: maths

I think I will give a go. If I can pull off 48 or over in mx1, I will definitely do it.

thats good to hear, cause your definitely talented enough
i couldnt believe you were considering not doin it
say you do get 48 in 3 unit this year,
and next year you do 4 unit, will that 48 get changed to 96??

by the way, howd you go in the trials for 3 unit??

 

[lyounamu]

Re: maths

thats good to hear, cause your definitely talented enough
i couldnt believe you were considering not doin it
say you do get 48 in 3 unit this year,
and next year you do 4 unit, will that 48 get changed to 96??

Either 96 or 97.

My friend got 48 but he got 97 when he got his HSC results back.

My other friend got 49 but he got 99 when he got the results back.

 

[bubblesss]

maths help needed ASAP

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

thanks in advance.

 

[squeenie]

Re: maths help needed ASAP

tan (x-60) = sqrt(3)
x-60 = 30 degrees (tan sqrt(3) = 30, using exact values)
therefore, x = 90

... I think that's right...

Edit: Wait, no...

since tan sqrt(3) = 30, tan (x-60) = 30

therefore, x = 90.

 

[tommykins]

Re: maths help needed ASAP

From your exact triangles, we know that tan (pi/3) = sqrt3

But since sqrt3 is negative, we need to find the domains in which tan is negative.

ASTC

We're in the second and fourth quadrant

x - pi/3 = 2pi/3 and 5pi/3

Thus, x = pi and 2pi

 

[tacogym27101990]

Re: maths help needed ASAP

tan(x-60) = -rt3
so x-60 = -60 , 120, 300, ...

x= 0, 180, 360 for 0 =<x=<360

i hate degrees these days, radians is so much neater

 

[tommykins]

Re: maths help needed ASAP

tan(x-60) = -rt3
so x-60 = -60 , 120, 300, ...

x= 0, 180, 360 for 0 =<x=<360

i hate degrees these days, radians is so much neater

<3 pi

 

[bubblesss]

Re: maths help needed ASAP

tan(x-60) = -rt3
so x-60 = -60 , 120, 300, ...

x= 0, 180, 360 for 0 =<x=<360

i hate degrees these days, radians is so much neater

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

 

[tommykins]

Re: maths help needed ASAP

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

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.