3U Maths Question Thread

[RuiAce]

oh lol ok and also for questions asking "find the angle when the projectile hits the ground" If i find the y velocity and x velocity then just do tan theta, do i have to minus the answer from 180 degrees?

[bethjomay]

Wondering if someone could help me out with a standard process for drawing inverse trig graphs? I always get myself mixed up.

[RuiAce]

Wondering if someone could help me out with a standard process for drawing inverse trig graphs? I always get myself mixed up.

It's the same as with any graph. Provide a question if you want a specific demo

[bethjomay]

This is a pretty simple one, but I'm not sure where to start with it (part a)

[imtrying]

I a bit out of practice with general solutions...could someone explain why the answer is B and not A please? Thanks!

[jakesilove]

This is a pretty simple one, but I'm not sure where to start with it (part a) (Image removed from quote.)

Hey! I could never remember how to plot things like this in my HSC year, and tbh I never learned how to do it either. I just plotted points until I understood the general shape of the graph (using my calculator) and sketched it from there! I would highly recommend doing this, as you'll get the answer 100% of the time. Alternatively, recall the shape of the inverse cos graph. It has domain between -1 and 1, and range between 0 and Pi. The 3 'amplitude' will triple the height, so the range will be between 0 and 3Pi. The 2 will half the 'period', making the graph skinnier, so the domain will be between 1/2 and -1/2. The shape of the graph will be the same!

[RuiAce]

Hey! I could never remember how to plot things like this in my HSC year, and tbh I never learned how to do it either. I just plotted points until I understood the general shape of the graph (using my calculator) and sketched it from there! I would highly recommend doing this, as you'll get the answer 100% of the time. Alternatively, recall the shape of the inverse cos graph. It has domain between -1 and 1, and range between 0 and Pi. The 3 'amplitude' will triple the height, so the range will be between 0 and 3Pi. The 2 will half the 'period', making the graph skinnier, so the domain will be between 1/2 and -1/2. The shape of the graph will be the same!

lol.

Basically it, but I'll post a somewhat more formalised approach soon. I don't advise against this trick method though

[jakesilove]

I a bit out of practice with general solutions...could someone explain why the answer is B and not A please? Thanks!

Hey! Always just use the general solution on your Mathematics Ext 1 reference sheet. That should get you a solution of 2x equal to the formula sheet result, which is



Divide the whole thing by two, which gives you the answer of B

Jake

[bethjomay]

Hey! I could never remember how to plot things like this in my HSC year, and tbh I never learned how to do it either. I just plotted points until I understood the general shape of the graph (using my calculator) and sketched it from there! I would highly recommend doing this, as you'll get the answer 100% of the time. Alternatively, recall the shape of the inverse cos graph. It has domain between -1 and 1, and range between 0 and Pi. The 3 'amplitude' will triple the height, so the range will be between 0 and 3Pi. The 2 will half the 'period', making the graph skinnier, so the domain will be between 1/2 and -1/2. The shape of the graph will be the same!

Awesome thank you! Good to hear I'm not the only one who does that.

[jakesilove]

Awesome thank you! Good to hear I'm not the only one who does that.

It's how I sketched basically every trig related function in Ext 1

[imtrying]

Hey! Always just use the general solution on your Mathematics Ext 1 reference sheet. That should get you a solution of 2x equal to the formula sheet result, which is



Divide the whole thing by two, which gives you the answer of B

Jake

Thanks😄

[bethjomay]

So like this? Is that adequately 'indicating the domain and range?'

[jakesilove]

(Image removed from quote.)

So like this? Is that adequately 'indicating the domain and range?'

Yep, that's absolutely perfect This could be a nasty habit of mine from doing Ext 2, but I would always write 'x' and 'y' on my two axes. Just me being nit-picky aha

[RuiAce]

This is a pretty simple one, but I'm not sure where to start with it (part a) (Image removed from quote.)

Info has been presented here on GeoGebra as a demo. You should consider showing one graph at a time as well as comparing two or three at a time.

That being said I always use Jake's method to check my working out.


Edit: Yeah that graph is good. And @Jake nah that x and y on the axes should definitely be there

[bethjomay]

Ok, thank you both! That's good to know about the x and y, I do it sometimes but I was never sure if it was required!