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keelyjm
 3 years ago
Help finding exact values.
keelyjm
 3 years ago
Help finding exact values.

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keelyjm
 3 years ago
Best ResponseYou've already chosen the best response.0Find an exact value. sin 75°

keelyjm
 3 years ago
Best ResponseYou've already chosen the best response.0\[\frac{ \sqrt{6}+\sqrt{2} }{ 4 }\] Is this right?

ZeHanz
 3 years ago
Best ResponseYou've already chosen the best response.1It is right, but what kind of help are you looking for?

keelyjm
 3 years ago
Best ResponseYou've already chosen the best response.0I do not know how to do it, but looking at a unit circle that seemed correct with where the angle should be. I want to know what equatin to use to get that answer for future use.

ZeHanz
 3 years ago
Best ResponseYou've already chosen the best response.1Do you know the formula: sin(a+b)=sin(a)cos(b)+cos(a)sin(b)?

keelyjm
 3 years ago
Best ResponseYou've already chosen the best response.0Like currently I am stuck on Find an exact value. sine of negative eleven pi divided by twelve.\[\sin(\frac{ 11\pi }{ 12 })\]

keelyjm
 3 years ago
Best ResponseYou've already chosen the best response.0I am not familiar with that equation.

ZeHanz
 3 years ago
Best ResponseYou've already chosen the best response.1OK, that makes it a lot more difficult, I guess. sin(11pi/12)=sin(11pi/12)=sin(pi/12)=sin(15°) Have you been instructed to do these kind of problems in a unit circle?

keelyjm
 3 years ago
Best ResponseYou've already chosen the best response.0yes to find the final answer.

ZeHanz
 3 years ago
Best ResponseYou've already chosen the best response.1OK, I'll try to draw one...

keelyjm
 3 years ago
Best ResponseYou've already chosen the best response.0I have a pic in front of me that I drew

phi
 3 years ago
Best ResponseYou've already chosen the best response.3I think you try to use "nice numbers" that add or subtract to get 75º 45º + 30º = 75º

phi
 3 years ago
Best ResponseYou've already chosen the best response.3now use sin(a+b)= sin(a)cos(b) + cos(a) sin(b)

keelyjm
 3 years ago
Best ResponseYou've already chosen the best response.0I already figured that one out. I am working on\[\sin(\frac{ 11\pi }{ 12 })\]

phi
 3 years ago
Best ResponseYou've already chosen the best response.3I (for one) switch to degrees first.

phi
 3 years ago
Best ResponseYou've already chosen the best response.3multiply by 180/pi you get 165 degrees that means go clockwise from the xaxis. as a positive angle it is 360165= 195 degrees so you want to find the sin(15) in the 3rd quadrant

keelyjm
 3 years ago
Best ResponseYou've already chosen the best response.0So I would do sin(4530)

mariomintchev
 3 years ago
Best ResponseYou've already chosen the best response.0phi, when you're done here, can you come back to my problem? thanks!

keelyjm
 3 years ago
Best ResponseYou've already chosen the best response.0so would I do sin(45)cos(30)cos(45)sin(30) next?

phi
 3 years ago
Best ResponseYou've already chosen the best response.3yes, but remember that sin is negative in the 3rd quadrant so minus the final answer

keelyjm
 3 years ago
Best ResponseYou've already chosen the best response.0So how would I do that? I am thinking the answer would be \[\frac{ \sqrt{6}\sqrt{2} }{ 4 }\] Just from what I know so far and the unit circle.

phi
 3 years ago
Best ResponseYou've already chosen the best response.3sin(45)cos(30)cos(45)sin(30) should give you \[ \frac{ \sqrt{6}\sqrt{2} }{ 4 }\] now negate it to get \[ \frac{ \sqrt{2}\sqrt{6} }{ 4 }\]

phi
 3 years ago
Best ResponseYou've already chosen the best response.3you can always check your answers using a calculator. sin(165º) = 0.2588...

keelyjm
 3 years ago
Best ResponseYou've already chosen the best response.0Oh I wrote it wrong and forgot to negate it

phi
 3 years ago
Best ResponseYou've already chosen the best response.3so to do these problems, figure out the "reference angle" (that is the angle less than 90 that you make with the xaxis) and what quadrant. try to come up with sums or differences that give the reference angle and then use the formulas finally, use the quadrant to assign the correct sign.

keelyjm
 3 years ago
Best ResponseYou've already chosen the best response.0Alright I will have to write that down. Thank you.

ZeHanz
 3 years ago
Best ResponseYou've already chosen the best response.1@keelyjm: I thought you weren't familiar with sin(a+b)=sin(a)cos(b)+cos(a)sin(b)? Now you are using it... Glad you do, because it makes everything much easier ;)

keelyjm
 3 years ago
Best ResponseYou've already chosen the best response.0Yeah after I saw that with unusual angles you had to split it into to normal angles I got where a and b went

keelyjm
 3 years ago
Best ResponseYou've already chosen the best response.0and basically I figured out how to use the equation
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