lisaboden54021 lisaboden54021
  • 26-04-2018
  • Mathematics
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Find the exact value of the trigonometric expression given cos (22.5 ).

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Аноним Аноним
  • 29-04-2018
use the identity   cos^2 (a/2) =  1/2 (1 + cos a) so

cos^ 2 22.5  = cos^2 (45/2)  = 1/2 ( 1 + cos 45)  =  1/2(1 + sqrt2/ 2)4 = 1/2 + sqrt2/4

cos 22.5  =  sqrt ( 1/2 + sqrt2/4)  Answer
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