View Full Version : Algebraic Brain Explosion
Goldenboko
01-12-2009, 11:49 PM
So, I've got something I know will be included in a test tomorrow (the test isn't on it, but it's a little detail which will end up hurting me D: ).
Apparently fractions inside square roots are no-goes. So when you have something that looks like sqrt(1-sqrt(3)/2) you have to get rid of the two. My book ends up showing the answer as 1/2sqrt(2-sqrt(3)) Which confuses me, how did they simplify to get that?
If it helps here's the original question, "Use the half-angle formulas to determine the exact value of the sin 105 degrees".
Jessweeee♪
01-13-2009, 12:06 AM
uhh...so is that one part sqrt<sup>3</sup>/<sub>2</sub> or sqrt3 divided by 2? It's so hard to read radicals this way ;_;
Goldenboko
01-13-2009, 12:09 AM
Oh whoops.
sqrt((1-sqrt(3))/2)
Flying Mullet
01-13-2009, 12:13 AM
See if this helps you write out your formulas:
1 - (√3)/2
Jessweeee♪
01-13-2009, 12:30 AM
...I didn't think you could have a radical in a radical if you couldn't have a fraction in a radical, math is weeeird.
I got
(<sup>1</sup>/<sub>2</sub>)√(2-2√(3))
if that's what you meant to type in the first post then I can help, if not then I'm doing it wrong and will be useless xD
Goldenboko
01-13-2009, 12:40 AM
Redid the problem, basic math error in the beginning screwed me later on. I'm good :thumb:
rubah
01-13-2009, 12:41 AM
you can have a fraction in a radical, jesse. you just rewrite it as the square root of the numerator divided by the square root of the denominator, like √(1/2) = √(1)/√(2) then you can multiply top and bottom by √(2) to get rid of the square root in the denominator, but it's completely useless and only jerkfaces make you do that.
for √(1-√(3)/2) you'd multiply the two terms inside the outer √ by two but you'd have to divide by √2 twice on the outside, so:
√((1*2) - 2√(3)/2)) * (1/√(2)) * (1/√(2))
so that simplifies to
√(2 - √(3)) * (1/√(2))<sup>2</sup>
the √ and <sup>2</sup> cancel (square root is basically <sup>1/2</sup> so you multiply them out to get 1) so you just get *(1/2)
[edit- grrrrrrrrrrrrrr gobo!]
I'm just squinting at this thread in confusion, trying to remember when I've learned this. I've taken up to Pre-Calc in math, so I must have, but jeez.
Oh well. I finished all of my math requirements in college, I never have to do any advanced math again! And my Science credit will be down after I take Bio, so I won't even need to solve Chem equations. YAY! ♥
Good luck!
Jessweeee♪
01-13-2009, 01:16 AM
I hate chemistry equations. I hate them. My math and my science grades are always totally opposite for the same reason! Math!
Aerith's Knight
01-13-2009, 08:29 PM
I always think: "Finally a math problem, not some kind of Japanese, post-modern American studies crap." but when I get there everything is already solved. ;_;
I HATE YOU! jk, just mildly despise
rubah
01-13-2009, 08:47 PM
that's because we all think the same thing and hurry to beat each other to be the one to answer.
Goldenboko
01-13-2009, 09:09 PM
I love asking the question and watching the ensuing dogfight =D
Jessweeee♪
01-13-2009, 10:54 PM
We all gotta look smart, you know :(
scrumpleberry
01-13-2009, 10:59 PM
Make a maths nerdery thread!
Aerith's Knight
01-14-2009, 05:10 AM
Been there, done that.
Make a physics one instead. :)
blackmage_nuke
01-14-2009, 06:23 AM
We should make a maths social group where everyone can constantly try to out math each other.
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