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question about maths
Sweden m4st4m4st3r4wp 
so when i try to solve exactly what for example sin135 is. i start by changing 135 to (9pi)/2 and start solving. but then when i reach sin(pi/2)xcos(pi/4)+cos(pi/2)xsin(pi/4) sqrt2/2 i just check on my paper what like sin(pi/2) is and all the other ones so i can continue. but how do i solve what sin(pi/2) is? or is that just something you know without trying to solve it and just check on a paper?
2018-11-23 19:51
Slovakia WhitefoxSK 
2+2 is 4 minus 1 that's 3 quick maths
2018-11-23 19:53
juliano | 
El Salvador mikj 
135 is actually 5pi/4 firstly
2018-11-23 19:54
135 is 9pi/12???
2018-11-23 19:55
juliano | 
El Salvador mikj 
Yea soz it's pi/4 + pi /2 so 3pi/4
2018-11-23 19:56
juliano | 
El Salvador mikj 
And if you reach shit like this you have to use formula extensions for cos(2x) and sin(2x), but you have to match it to your argument Like cos(1/2x) = cos^2(1/4x) - sin^2(1/4x)
2018-11-23 19:58
ScreaM | 
Morocco Feit4N 
I dont know who the fuck give sin that name and decide all that shit, and I dont use it to win money or something thats why I dont give a damn about it
2018-11-23 19:58
United States gtmaniacmda 
memorize the unit circle /close
2018-11-23 19:59
yes i have done that. im just scared if i have to solve those on the test and not just know them.
2018-11-23 20:01
So ask your teacher if that might be on the test. They have plans they have to adhere to that states what you should know after their class, and their tests are made to reflect that. Not knowing what's on the test so you can't study for it is not really part of it.
2018-11-23 20:07
Germany Cr4zyy 
just imagine this on your unit circle and you will be able to read off your numbers sin (0°) = cos(270°) = sqrt(0)/2 sin (30°) = cos(300°) = sqrt(1)/2 sin(45°) = sin(pi/4) = cos(315°) = sqrt(2)/2 sin(60°) = cos(330°) = sqrt(3)/2 sin(90°) = sin(pi/2) = cos(0°) = sqrt(4)/2 and so on :)
2018-11-23 20:42
Turkey nt_forsaken 
i dont know but 45+45=90 90-45=45 45-45=0 90=0
2018-11-23 20:06
uninstall math, not needed in life <- pro C++ developer for 15+ years. only math needed: +-/*
2018-11-23 20:38
yeah im doing maths now so i can study programming program at university. i need more maths that i didnt get at high school and physics.
2018-11-23 20:46
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