Question 1042104
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Use a sum or difference formula to find the exact value of the following.

sin13π/18 cosπ/36 + cos13π/18 sinπ/36 =
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<pre>
{{{sin(13pi/18)*cos(pi/36) + cos((13pi)/18)*sin(pi/36)}}} = {{{sin((13pi)/18 + pi/36)}}} = {{{sin((26pi)/36 + pi/36)}}} = {{{sin(27pi/36)}}} = {{{sin((3pi)/4)}}} = {{{sqrt(2)/2}}}.
</pre>

Regarding a sum or difference formula, see the lesson

&nbsp;&nbsp;&nbsp;&nbsp;- <A HREF= http://www.algebra.com/algebra/homework/Trigonometry-basics/Addition-and-subtraction-formulas.lesson> Addition and subtraction formulas</A> 

in this site.