<PRE><B>Question 1150482</B>
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if a is in the third quadrant and cosa=15/17, find the value of cosa/2.
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If &amp;nbsp;&quot;a&quot; &amp;nbsp;is in the third quadrant, &amp;nbsp;then cos(a) &amp;nbsp;CAN &amp;nbsp;NOT &amp;nbsp;be equal to  &amp;nbsp;{{{15/17}}}.



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