Examine's 2u horrors (1 Viewer)

[Examine]

This is a thread where I poast maths questions that I have difficulty in which you can suggest a recommended approach for me to take. Don't want to flood the marathons so yeah.

HELPERS GET REPS AND EVERY1 KNOWS REP IS LYF

The current questions I'm having prawbrems in is:
Find all angles between 0 and 2pi which satisfy the following

secy=2cosy

1/cosy=2cosy

1=2cos^2y

And this is where I'm stuck/don't know what I do next or if I did it wrong.

Previously asked questions
Post 1, Page 1.
Post 13, Page 1.
Post 74, Page 5.

 

[zeebobDD]

cos^2y=1/2, then cosy=1/root2 then you find the angles from there.
correct me if im wrong havent

 

[RANK 1]

1/2 = cos^2y

1/(2)^1/2 = cos y

and you can go from there

 

[Carrotsticks]

cos^2y=1/2, then cosy=1/root2 then you find the angles from there.
correct me if im wrong havent

*

 

[Timske]

secy=2cosy

secy= 1/cosy

1/cosy=2cosy
1/cosy - 2cosy = 0
1 -2cos^2y = 0
cos^2y = 1/2
cosy = 1/root(2)

 

[SpiralFlex]

*Have you learnt where these formulae come from Examy? (From a geometrical perspective.)

 

[Timske]

im guessing you dont know your trig identities?

 

[Examine]

No I just have a tendency on looking at questions then giving up immediately.

I was a bit spooked about the 1 because I was thinking, w8, that's it? though it didn't seem right so I consulted with the internets.

So I guess what I'm saying is I lack the c00l sk1llz to pick up on the next step.

 

[RivalryofTroll]

secy=2cosy
1/cosy = 2cosy
2cos^2y = 1
cosy = + or - 1/root2
1st Quad 45
2nd Quad 180 - 45
3rd Quad 180 + 45
4th Quad 360 - 45
y = ABOVE SOLUTIONS

Where's my ten millions reps brutha?

 

[Examine]

At least I can do all the other questions now.

 

[Examine]

You must spread some Reputation around before giving it to RivalryofTroll again

 

[RivalryofTroll]

You must spread some Reputation around before giving it to RivalryofTroll again

I help you in Maths and you shall help me back in terms of Business Studies!
"If we help each other, we will all win" - Buddha

 

[Examine]

4sinx=3cosecx
4sinx=3/sinx
4sin^2x=3
sin^2x=3/4
sinx=+- root3/2

x=60,120,240,300

amirite internets?

 

[Examine]

I help you in Maths and you shall help me back in terms of Business Studies!
"If we help each other, we will all win" - Buddha

Good thing Business Studies is my forte.

 

[RivalryofTroll]

4sinx=3cosecx
4sinx=3/sinx
4sin^2x=3
sin^2x=3/4
sinx=+- root3/2

x=60,120,240,300

amirite internets?

4sinx - 3cosecx = 0
4sinx - 3/sinx = 0
4sin^2x - 3 = 0
sin^2x = 3/4
Yep sounds right!

 

[Examine]

*Have you learnt where these formulae come from Examy? (From a geometrical perspective.)

yup, just had a brainderp.

 

[Carrotsticks]

4sinx=3cosecx
4sinx=3/sinx
4sin^2x=3
sin^2x=3/4
sinx=+- root3/2

x=60,120,240,300

amirite internets?

Correct, but try to use radians if you can (if you have learnt them).

 

[Examine]

Correct, but try to use radians if you can (if you have learnt them).

The pi/3, 2pi/3, 4pi/3, 5pi/3?

 

[SpiralFlex]

I love how heaps of people are posting Harries questions.

More exposure Examy.

The pi/3, 2pi/3, 4pi/3, 5pi/3?

Make sure you know where it comes from too.

 

[twinklegal19]

That question was from Harry's trig hw, amirite?
How are you going with the quadratic polynomials stuff?