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keelyjmBest ResponseYou've already chosen the best response.0
Find an exact value. sin 75°
 one year ago

keelyjmBest ResponseYou've already chosen the best response.0
\[\frac{ \sqrt{6}+\sqrt{2} }{ 4 }\] Is this right?
 one year ago

ZeHanzBest ResponseYou've already chosen the best response.1
It is right, but what kind of help are you looking for?
 one year ago

keelyjmBest ResponseYou've already chosen the best response.0
I 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.
 one year ago

ZeHanzBest ResponseYou've already chosen the best response.1
Do you know the formula: sin(a+b)=sin(a)cos(b)+cos(a)sin(b)?
 one year ago

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

keelyjmBest ResponseYou've already chosen the best response.0
I am not familiar with that equation.
 one year ago

ZeHanzBest ResponseYou've already chosen the best response.1
OK, 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?
 one year ago

keelyjmBest ResponseYou've already chosen the best response.0
yes to find the final answer.
 one year ago

ZeHanzBest ResponseYou've already chosen the best response.1
OK, I'll try to draw one...
 one year ago

keelyjmBest ResponseYou've already chosen the best response.0
I have a pic in front of me that I drew
 one year ago

phiBest ResponseYou've already chosen the best response.2
I think you try to use "nice numbers" that add or subtract to get 75º 45º + 30º = 75º
 one year ago

phiBest ResponseYou've already chosen the best response.2
now use sin(a+b)= sin(a)cos(b) + cos(a) sin(b)
 one year ago

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

phiBest ResponseYou've already chosen the best response.2
I (for one) switch to degrees first.
 one year ago

phiBest ResponseYou've already chosen the best response.2
multiply 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
 one year ago

keelyjmBest ResponseYou've already chosen the best response.0
So I would do sin(4530)
 one year ago

mariomintchevBest ResponseYou've already chosen the best response.0
phi, when you're done here, can you come back to my problem? thanks!
 one year ago

keelyjmBest ResponseYou've already chosen the best response.0
so would I do sin(45)cos(30)cos(45)sin(30) next?
 one year ago

phiBest ResponseYou've already chosen the best response.2
yes, but remember that sin is negative in the 3rd quadrant so minus the final answer
 one year ago

keelyjmBest ResponseYou've already chosen the best response.0
So 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.
 one year ago

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

phiBest ResponseYou've already chosen the best response.2
you can always check your answers using a calculator. sin(165º) = 0.2588...
 one year ago

keelyjmBest ResponseYou've already chosen the best response.0
Oh I wrote it wrong and forgot to negate it
 one year ago

phiBest ResponseYou've already chosen the best response.2
so 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.
 one year ago

keelyjmBest ResponseYou've already chosen the best response.0
Alright I will have to write that down. Thank you.
 one year ago

ZeHanzBest 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 ;)
 one year ago

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

keelyjmBest ResponseYou've already chosen the best response.0
and basically I figured out how to use the equation
 one year ago
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