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trig mk7

-180°≤x≤180°

sin²(x+10)=0.8
sin(x+10)=√0.8
x+10=63.4 and 117
x=53.4 and 107

where are the other answers?
Original post by thefatone
-180°≤x≤180°

sin²(x+10)=0.8
sin(x+10)=√0.8
x+10=63.4 and 117
x=53.4 and 107

where are the other answers?


square-rooting 0.8 gives +√0.8 and -√0.8 hence two more values
Reply 2
Avatar for thefatone
thefatone
OP
6
Original post by TheSammy2010
square-rooting 0.8 gives +√0.8 and -√0.8 hence two more values


God dam everytime it's something.....

Spoiler

Reply 3
Avatar for TeeEm
TeeEm
19
Original post by TheSammy2010
square-rooting 0.8 gives +√0.8 and -√0.8 hence two more values


Original post by thefatone
-180°≤x≤180°

sin²(x+10)=0.8
sin(x+10)=√0.8
x+10=63.4 and 117
x=53.4 and 107

where are the other answers?


square rooting only gives one answer ... solving the equation correctly gives two.
Reply 4
Avatar for thefatone
thefatone
OP
6
Original post by TeeEm
square rooting only gives one answer ... solving the equation correctly gives two.


the back of the textbook say i should have 4 answers o.o
Original post by TeeEm
square rooting only gives one answer ... solving the equation correctly gives two.


If what you are saying is true, let me pose this question to you.

What's √4

If you say 2 and only 2, you have neglected negatives in the sense that -2 x -2 also equals 4.

So back to the original question, there are 4 roots given the interval.
Reply 6
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TeeEm
19
Original post by thefatone
the back of the textbook say i should have 4 answers o.o


the reference is on the outcome of the eqaution sin2 (x+10) =0.8
Reply 7
Avatar for TeeEm
TeeEm
19
Original post by TheSammy2010
If what you are saying is true, let me pose this question to you.

What's √4

If you say 2 and only 2, you have neglected negatives in the sense that -2 x -2 also equals 4.

So back to the original question, there are 4 roots given the interval.


you are posing me a question of that magnitude ?
well it is time for me to emigrate ...
Original post by TeeEm
the reference is on the outcome of the eqaution sin2 (x+10) =0.8


So? You will still get 4 answers?

Are you an A level student?
Reply 9
Avatar for TeeEm
TeeEm
19
Original post by TheSammy2010
So? You will still get 4 answers?

Are you an A level student?


It looks that as from tonight I have reached GCSE ...
Original post by TeeEm
It looks that as from tonight I have reached GCSE ...


Haha, no worries. You did have me questioning my math skills for a bit XD
Reply 11
Avatar for TeeEm
TeeEm
19
Original post by TheSammy2010
Haha, no worries. You did have me questioning my math skills for a bit XD


Your skills are not in question ... (at least for the time being ...)
your reasoning is ... since your post 6 is wrong but it is all good by me!!
b9.jpg
To summarise, sqrt(a) is always positive (assuming a>=0). But hence a^2=x ->a=+/-sqrt(x).
Original post by TeeEm
Your skills are not in question ... (at least for the time being ...)
your reasoning is ... since your post 6 is wrong but it is all good by me!!
b9.jpg


Haha yeah, true, now that I look back at it.
Reply 14
Avatar for Zacken
Zacken
22
Original post by TheSammy2010
If what you are saying is true, let me pose this question to you.

What's √4

If you say 2 and only 2, you have neglected negatives in the sense that -2 x -2 also equals 4.


That's wrong. 4=2\sqrt{4} = 2 and only 2. We define the map x↦xx \mapsto \sqrt{x} over R+→R+\mathbb{R}^{+} \to \mathbb{R}^+.
Original post by Zacken
That's wrong. 4=2\sqrt{4} = 2 and only 2. We define the map x↦xx \mapsto \sqrt{x} over R+→R+\mathbb{R}^{+} \to \mathbb{R}^+.


My text book never told me that. I'm only an A level student. I didn't even know what your comment means.
Reply 16
Avatar for Zacken
Zacken
22
Original post by TheSammy2010
My text book never told me that. I'm only an A level student. I didn't even know what your comment means.


As am I. Basically: x\sqrt{x} is a function that takes in positive x and outputs only positive y.

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