#I've been stuck on this for an hour and idk what to do

25 messages · Page 1 of 1 (latest)

glacial galleon
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I found that |c|=3√3, which I'm not certain about, but I don't rly know how to find the angle

static echo
glacial galleon
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Sure 1 sec

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I hope you can understand what I'm writing @static echo

Notes_221027_094553_1.jpg
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I know my handwriting isn't the best

static echo
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What is cos pi/3

glacial galleon
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1/2

static echo
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Seems alright

glacial galleon
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And I know that to find the angle I need to do like cos(x)=(a•c)/|a|•|c|

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I put • instead of *

static echo
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Ok

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Answer seems good to me

glacial galleon
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Something like cos(x)=(3√3)/2 which isn't right

static echo
glacial galleon
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I replaced c with (a+3b)

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And then I got a(a+3b) =|a|^2+ 3ab

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so 9+3*(3/2)

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Which is around 27/2

static echo
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a.(a+3b) = a.a + 3 (a.b) = 9 + 3 (3/2) = 27/2
Then a.c/|a| |c| = (27/2)/(3×(3sqrt(3)) = sqrt(3)/2

glacial galleon
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Wait what

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ohhhh wait

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I see what I did wrong

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I completely ignored the |a| by accident

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Ty