Halils Help Thread for Specialist

[Halil]

Question is:

Find the exact value of the following



I turned it into 1/sin(5pie/12)

then used

In the end i got



which also equals to:



However, answer is just 

How? What did I do wrong?

[Halil]

Sorry i dont know why it came out like that, the &#8730 ones means square root and the 960 ones are pie

[Halil]

Exactly same problem and and answer for sec (pie/12)

[pi]

Fixed it for you.

For next time:
π or pie (no) or pi = \pi
√ = \sqrt{...}
For fractions = \frac{...}{...}

Question is:

Find the exact value of the following



I turned it into

then used

In the end i got



which also equals to:



However, answer is just  

How? What did I do wrong?

Exactly same problem and and answer for sec (pie/12)

Its 'pi'...

[pHysiX]

Hint: rationalise and you shall have your answer. Remember, to be mathematically elegant, we never want surds in the denominator.