What is the exact value of sin(pi/12)

**skeske1234** · April 6th 2009, 10:43 AM

What is the exact value of sin(pi/12)

Explain how you get it

**stapel** · April 6th 2009, 10:51 AM

Originally Posted by skeske1234

Explain how you get it

Explain how one gets what? There is no question in your post.

Are you maybe referring to the contents of your subject line...? If so, then try using the same sort of technique which was provided to you here.

If you get stuck, please reply showing how far you have gotten, starting with how you turned 1/12 into a sum or difference of 1/2, 1/3, 1/4, and / or 1/6, and showing which trig identity you are using. Thank you!

**skeske1234** · April 6th 2009, 10:56 AM

I don't know what compound angle formula to use for
sin(pi/12)
because pi/12 = 15 degrees... There is no special angle that will add up to that.
What is another method I could use?

**stapel** · April 6th 2009, 11:08 AM

So try doing subtractions....

**skeske1234** · April 6th 2009, 11:13 AM

Originally Posted by stapel

So try doing subtractions....

OHHHHHHHSDLKJGHDSKJGHSDJ omg . k.

wow -.-

**Hush_Hush** · April 6th 2009, 11:33 AM

Hello,

U have this formula:

$sin^2(x)=\frac{1-cos(2x)}{2}\Rightarrow sin(x)=\sqrt{\frac{1-cos(2x)}{2}}$

$sin(\frac{\pi}{12})=\sqrt{\frac{1-cos(\frac{\pi}{6})}{2}}$

$sin(\frac{\pi}{12})=\sqrt{\frac{1-\frac{\sqrt{3}}{2}}{2}}$

Also u can have the next method

$sin(\frac{\pi}{4}-\frac{\pi}{6})=sin(\frac{\pi}{4})cos(\frac{\pi}{6} )-sin(\frac{\pi}{6})cos(\frac{\pi}{4})$

$sin(\frac{\pi}{4}-\frac{\pi}{6})=\frac{\sqrt{2}}{2}*\frac{1}{2}-\frac{\sqrt{3}}{2}*\frac{\sqrt{2}}{2}$

Have a nice day,

Hush_Hush.

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