Posted by Abby on Sunday, February 28, 2010 at 11:40am.
1) Use the cofunction identites to evaluate the expression without the aid of a calculator.
cos^2 18 degrees + cos^2 72 degrees.
Would I use the forumula
cos(pi/2  Q) = sin Q

Math(Please check)  Reiny, Sunday, February 28, 2010 at 12:06pm
see previous post
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