Anything I try fails. | Mathematics | Page 1

sleek spear Oct 13, 2023, 2:20 PM

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gaunt fogBOT Oct 13, 2023, 2:20 PM

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sleek spear

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misty tundra Oct 13, 2023, 2:26 PM

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What did you try?

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@sleek spear Which one do you have problems with?

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For "a" use the Pythagorean theorem.

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And "b" I believe the cosine rule.

sleek spear Oct 13, 2023, 2:29 PM

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I tried both and it doesn’t say which I got wrong.

19^(2)+19^(2) = 722
Square root of 722 = 26.9 (1 d.p or 3 s.f)

sleek spear Oct 13, 2023, 2:29 PM

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misty tundra And "b" I believe the cosine rule.

That might be where I went wrong

misty tundra Oct 13, 2023, 2:29 PM

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Ok A is right.

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Do you know the cosine rule?

sleek spear Oct 13, 2023, 2:30 PM

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Yes

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A^(2) = b^(2) + c^(2) - 2bccos(x)

misty tundra Oct 13, 2023, 2:31 PM

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So angle should be 82.

sleek spear Oct 13, 2023, 2:31 PM

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Mhm.

misty tundra Oct 13, 2023, 2:31 PM

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One side should be sqrt(722)/2

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Can you see that?

sleek spear Oct 13, 2023, 2:31 PM

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Yeah

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Just need the length of oc

misty tundra Oct 13, 2023, 2:33 PM

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🤔

sleek spear Oct 13, 2023, 2:33 PM

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Wouldn’t that use cos

misty tundra Oct 13, 2023, 2:33 PM

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Cos is adjacent by hypotenuse.

sleek spear Oct 13, 2023, 2:33 PM

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Yep

misty tundra Oct 13, 2023, 2:33 PM

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We don't know hypotenuse nor what cos is.

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Maybe we are using the wrong formula.

sleek spear Oct 13, 2023, 2:34 PM

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Well we have the adjacent.

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and we can label the hypotenuse as x

misty tundra Oct 13, 2023, 2:34 PM

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19/x = cos(82)?

sleek spear Oct 13, 2023, 2:35 PM

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Where'd you get the 19 from?

misty tundra Oct 13, 2023, 2:35 PM

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The side.

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The square base thing.

sleek spear Oct 13, 2023, 2:35 PM

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Oh yeah

misty tundra Oct 13, 2023, 2:35 PM

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Try to find what x is.

sleek spear Oct 13, 2023, 2:36 PM

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I think its more around cos(82) = sqrrt(722)/x

misty tundra Oct 13, 2023, 2:36 PM

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A.K.A Hypotenuse.

sleek spear Oct 13, 2023, 2:36 PM

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given AC is sqrrt(722).
Adjacent is half of that

misty tundra Oct 13, 2023, 2:36 PM

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Oh yea.

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Can't believe I forgot about that.

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Try to find Hypotenuse.

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And from that we can use the Cosine rule.

sleek spear Oct 13, 2023, 2:37 PM

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sqrrt(722)/cos(82)?

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28.3 (rounded to 1 d.p.)

misty tundra Oct 13, 2023, 2:38 PM

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Cos(82) = sqrt(722)/2/x.

sleek spear Oct 13, 2023, 2:38 PM

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oh yeah

misty tundra Oct 13, 2023, 2:39 PM

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Ok tell me what you find for x.

sleek spear Oct 13, 2023, 2:40 PM

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16.4 to 1 d.p

misty tundra Oct 13, 2023, 2:41 PM

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I got 14.1.

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Wait let me substitutie that in my calculator.

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Cos 82 is 0.95.

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Sqrt(722)/2/16.4 is 0.82.

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And 14.1 is 0.952.

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And cos is like 0.949.

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I think it might have to do with shortening it.

sleek spear Oct 13, 2023, 2:44 PM

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Yeah

misty tundra Oct 13, 2023, 2:44 PM

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Yea I think 14.1 is correct.

sleek spear Oct 13, 2023, 2:44 PM

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Alright

misty tundra Oct 13, 2023, 2:44 PM

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So we know hypotenuse is 14.1.

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Can you do it from here?

sleek spear Oct 13, 2023, 2:46 PM

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180.5 + 198.81 - 2*(sqrt(722)/2)*14.1*cos(82)?

misty tundra Oct 13, 2023, 2:47 PM

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Tell me what you will find for the height.

sleek spear Oct 13, 2023, 2:47 PM

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19.4 (3 s.f.)

misty tundra Oct 13, 2023, 2:48 PM

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What does Khan say?

sleek spear Oct 13, 2023, 2:48 PM

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Khan?

misty tundra Oct 13, 2023, 2:48 PM

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Isn't this in Khan Academy?

sleek spear Oct 13, 2023, 2:48 PM

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Nope.

misty tundra Oct 13, 2023, 2:48 PM

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Well what does it say?

sleek spear Oct 13, 2023, 2:49 PM

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Well as stated in the beginning it wont state if it was right or wrong.

misty tundra Oct 13, 2023, 2:49 PM

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Oh so we just enter it and hope for the best?

sleek spear Oct 13, 2023, 2:49 PM

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Yep

misty tundra Oct 13, 2023, 2:49 PM

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Ok then let me look at the calculations.

sleek spear Oct 13, 2023, 2:49 PM

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Aaaand it was wrong (we have a second attempt)

misty tundra Oct 13, 2023, 2:50 PM

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Ok so what I got was 18.07.

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But wait.

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Ok I believe it's 18.07.

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So try inserting 18.1

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And hope for the best.

sleek spear Oct 13, 2023, 2:53 PM

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so
A) 26.9
B is 18.1?

misty tundra Oct 13, 2023, 2:53 PM

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Wdym?

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What is 26.9?

sleek spear Oct 13, 2023, 2:53 PM

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We calculated A at the beginning

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the length A-C

misty tundra Oct 13, 2023, 2:54 PM

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That was sqrt(722)/2.

sleek spear Oct 13, 2023, 2:54 PM

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Sqrt(722)/2 was AC halved

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since Sqrt(722) was AC and the adjancent was half AC

misty tundra Oct 13, 2023, 2:54 PM

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Wait.

sleek spear Oct 13, 2023, 2:54 PM

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In the beginning of the chat.

misty tundra Oct 13, 2023, 2:55 PM

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We think the Hypotenuse is 14.1 right?

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What if we just use Pythagorean?

sleek spear Oct 13, 2023, 2:55 PM

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Yeah.

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Fair point

misty tundra Oct 13, 2023, 2:55 PM

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That will for sure confirm the answer.

sleek spear Oct 13, 2023, 2:56 PM

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14.1^(2) + (sqrt(722)/2)^(2)

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198.81 + 180.5 = 379.31

misty tundra Oct 13, 2023, 2:56 PM

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19.475?

sleek spear Oct 13, 2023, 2:57 PM

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yeah

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that seems correct