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how to get these answers

how can u get the answer which I highlight in green here?I think they are simple questions but I cannot get the correct answerIMG_20200509_120132-compressed.jpg.jpegIMG_20200509_120035-compressed.jpg.jpegIMG_20200509_120025-compressed.jpg.jpeg
Reply 1
Avatar for Foxehh
Foxehh
21
Math hurts my brain
Reply 2
Avatar for mqb2766
mqb2766
21
Original post by Hedwigeeeee
how can u get the answer which I highlight in green here?I think they are simple questions but I cannot get the correct answerIMG_20200509_120132-compressed.jpg.jpegIMG_20200509_120035-compressed.jpg.jpegIMG_20200509_120025-compressed.jpg.jpeg

For 7, you should be using radians, not degrees.
Original post by mqb2766
For 7, you should be using radians, not degrees.

I used radians，not degrees
Reply 4
Avatar for mqb2766
mqb2766
21
Original post by Hedwigeeeee
I used radians，not degrees

But you have acos(1/3) ~ 60?
Original post by mqb2766
But you have acos(1/3) ~ 60?


IMG_20200509_180745-compressed.jpg.jpeg
Reply 6
Avatar for mqb2766
mqb2766
21
Original post by Hedwigeeeee
IMG_20200509_180745-compressed.jpg.jpeg

That is degrees not radians.
Original post by mqb2766
That is degrees not radians.


u mean transfer 8.398 to radians?
Reply 8
Avatar for mqb2766
mqb2766
21
Original post by Hedwigeeeee
u mean transfer 8.398 to radians?

No, youve rooted it. Transform to radians before rooting.
Or set your calculator in radians mode.
Original post by mqb2766
No, youve rooted it. Transform to radians before rooting.
Or set your calculator in radians mode.


but that one gives no answer...IMG_20200509_184459-compressed.jpg.jpeg
Original post by Hedwigeeeee
but that one gives no answer...IMG_20200509_184459-compressed.jpg.jpeg

Your calculator is still set to degrees.
SHIFT
SETUP
2
2
Original post by BuryMathsTutor
Your calculator is still set to degrees.
SHIFT
SETUP
2
2

so how can I do it with degrees？with degrees, I did (arccos(1/3))^0.5, and I convert the final answer to radians, but I got 0.147
Original post by Hedwigeeeee
so how can I do it with degrees？with degrees, I did (arccos(1/3))^0.5, and I convert the final answer to radians, but I got 0.147

There's no reason to be doing this in degrees.
Enter
1 =
and then continue as in the image below, repeatedly pressing =.
Untitled.jpg60.5KB
Original post by BuryMathsTutor
There's no reason to be doing this in degrees.
Enter
1 =
and then continue as in the image below, repeatedly pressing =.

I have never tried that button to convert degree to radians! so why here we should use radians here?I cannot just use the degree form and convert sth by divide or multiply 180/pi? when I should convert degree to radians form?
Original post by Hedwigeeeee
I have never tried that button to convert degree to radians! so why here we should use radians here?I cannot just use the degree form and convert sth by divide or multiply 180/pi? when I should convert degree to radians form?


If a question is in radians, use radians on the calculator. I’m shocked your teacher never told you this.
Original post by Jamie_1712
If a question is in radians, use radians on the calculator. I’m shocked your teacher never told you this.

we normally use 180/pi to convert, but I found it wrong here. so I can't use any degree forms here right? and there is no way to convert?
Original post by Hedwigeeeee
we normally use 180/pi to convert, but I found it wrong here. so I can't use any degree forms here right? and there is no way to convert?

You could do that after the acos, but before the root, as mentioned above.
Simplest way is to put your calculator in radians mode.
Original post by mqb2766
You could do that after the acos, but before the root, as mentioned above.
Simplest way is to put your calculator in radians mode.


ahhhhh，I think I shold convert before squaring root! thank u
Original post by Hedwigeeeee
ahhhhh，I think I shold convert before squaring root! thank u

Easier to use radians onyour calculator, but doing that is ok.

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