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rubyhunter
 3 years ago
if cos x = 4/11 find cos 2A (HELP PLEASE)
rubyhunter
 3 years ago
if cos x = 4/11 find cos 2A (HELP PLEASE)

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maym0Re97
 3 years ago
Best ResponseYou've already chosen the best response.1by 2A do you mean 2x?

maym0Re97
 3 years ago
Best ResponseYou've already chosen the best response.1If that's the case, then your'e going to do arc cos of 4/11, which yields x, then plug that value of x into cos2x

rubyhunter
 3 years ago
Best ResponseYou've already chosen the best response.0i dnt get ti can you walk me through it

maym0Re97
 3 years ago
Best ResponseYou've already chosen the best response.1ok so by 2A did you actually mean cos2x?

shubhamsrg
 3 years ago
Best ResponseYou've already chosen the best response.2why dont you simply use this gem of a formulla : cos 2x = (2cos^2 x)  1 hope this helps..

rubyhunter
 3 years ago
Best ResponseYou've already chosen the best response.0no it doesnt help CAUSE I DNT KNOW HOW TO DO IT :(

shubhamsrg
 3 years ago
Best ResponseYou've already chosen the best response.2nevermind,,i cant help you further then :/

maym0Re97
 3 years ago
Best ResponseYou've already chosen the best response.1Ok so use your graphing calculator and there should be a button that's like cos, and right above it you'll see cos^1. Plug into your calcultar, cos^1(4/11), because what that's saying is cos of the whatever that is, is going to be 4/11. Now you have x. Now plug whatever you got for x back into your calculator.

maym0Re97
 3 years ago
Best ResponseYou've already chosen the best response.1Back into the equation cos2x.

rubyhunter
 3 years ago
Best ResponseYou've already chosen the best response.0wait y am i doin cos1 instead of cos

maym0Re97
 3 years ago
Best ResponseYou've already chosen the best response.1because that's how you're going to find x. It's just like how if you had x^2=4, you'd find the square root of both sides. In this case you're getting rid of the cos.

maym0Re97
 3 years ago
Best ResponseYou've already chosen the best response.1ok, so is that what you're getting for cos^1(4/11)?

maym0Re97
 3 years ago
Best ResponseYou've already chosen the best response.1ok you have that value for x, now plug that in for x in cos2x. So plug in cos(2*68.67). That SHOULD be how you do it, I haven't done stuff like this in two years.

rubyhunter
 3 years ago
Best ResponseYou've already chosen the best response.0so is it a .7353878608

maym0Re97
 3 years ago
Best ResponseYou've already chosen the best response.1Yeah uhhhh that should be it, apologies if it isn't though, I don't have a calculator with me.

jishan
 3 years ago
Best ResponseYou've already chosen the best response.0use to apply cos2x=cos^2xsin^2x cox=4/11 sinx=squareroot( 1cos^2x)
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