Prelim 2016 Maths Help Thread (2 Viewers)

[jathu123]

1/sinθ = -2
-2sinθ = 1
sinθ = -1/2
acute angle is 30
so θ = (180+30), (360-30)
θ = 210, 330

 

[eyeseeyou]

1/sinθ = -2
-2sinθ = 1
sinθ = -1/2
acute angle is 30
so θ = (180+30), (360-30)
θ = 210, 330

Jathu123

Try my motion Q's

 

[jathu123]

Jathu123

Try my motion Q's

haven't done motions yet soz

 

[eyeseeyou]

haven't done motions yet soz

Okay get someone else to do them then

What have you done Jathu123

 

[drsabz101]

thanks heaps

 

[eyeseeyou]

Q:

Two model rockets launched from two different launch pads G & D. From an observation site, O, rocket A has been launched at N28 degrees WEST and rocket B has been luanched at N40 degrees EAST. The angle of elevation from the observation location is 29 degrees for rocket A and 37 degrees for rocket B. If the distance between the observation site and launch pad G is 120m and the distance from observation site to a launch pad D is 80m, what is the distance between the two rockets AFTER THE LAUNCH.

 

[eyeseeyou]

This thread needs a name change to "prelim maths thread" b/c I'm sure ppl in the lower years are going to use it

 

[leehuan]

Motion isn't even a prelim topic.

 

[eyeseeyou]

Motion isn't even a prelim topic.

Yeah ik

 

[drsabz101]

solve for alpha

 

[eyeseeyou]

...what are we even doing with these expressions??

I think solve for aplha

 

[InteGrand]

these 2 q. :

View attachment 33227
View attachment 33228

 

[eyeseeyou]

Q:

Two model rockets launched from two different launch pads G & D. From an observation site, O, rocket A has been launched at N28 degrees WEST and rocket B has been luanched at N40 degrees EAST. The angle of elevation from the observation location is 29 degrees for rocket A and 37 degrees for rocket B. If the distance between the observation site and launch pad G is 120m and the distance from observation site to a launch pad D is 80m, what is the distance between the two rockets AFTER THE LAUNCH.

Integrand

Try this

 

[drsabz101]

Can someone show the steps for solving these questions... I am not getting these:

 

[eyeseeyou]

Can someone show the steps for solving these questions... I am not getting these:
View attachment 33231

Help bump

Also help me with my question above

 

[eyeseeyou]

How is this a 1-1 function

x 0 1 2 3 4
y 0 1 4 5 6

There's a 0 for x and a 0 for y???

 

[eyeseeyou]

Also how do I sketch the following inverse functions

1. y=2-e^x
2. y=sinx
3. y=cos2x, 0≤x≤π/2

 

[eyeseeyou]

For some reason I got this question wrong:

Find the inverse function of the following. Also state the domain and range of the inverse function

a. y=(x-2)/(x+2)

Someone plz tell me what I did wrong. I got y=xy+2x+2 as an answer but that is wrong???

 

[leehuan]

For some reason I got this question wrong:

Find the inverse function of the following. Also state the domain and range of the inverse function

a. y=(x-2)/(x+2)

Someone plz tell me what I did wrong. I got y=xy+2x+2 as an answer but that is wrong???

x=(y-2)/(y+2)
xy+2x=y-2

So that's not wrong, what you have there... per se

You left a y on the RHS, which you should never do. In other words you did not finish the question

y-xy = (2x+2)
y(1-x) = 2(x-1)
y = 2[(1+x)/(1-x) ]

 

[leehuan]

How is this a 1-1 function

x 0 1 2 3 4
y 0 1 4 5 6

There's a 0 for x and a 0 for y???

At the HSC level (since you don't know what a codomain is yet) a function is one-to-one iff every one value of x carries only ONE value for y.

If x and y happen to equal to the same thing that means jack shit. It's that for every x-value, there can be at most one y-value.

If x=0 then y=0 and y=1 SIMULTANEOUSLY then it's no longer one-to-one