double angle trigonometry

if sin data =2/5 what is the exact value of cos 20?

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if sin data =2/5 what is the exact value of cos 20?
jay12345678987
23 April 2013
if sin data =2/5 what is the exact value of cos 20?
jay12345678987
23 April 2013
What do you mean by sin data? Do you mean sin20 = 2/5?
Mark B.
25 April 2013
Trig2.JPG (18.5 KB)
Mark B.
25 April 2013
Trig1.JPG (25.1 KB)
Mark B.
25 April 2013
Do you mean if sin theta = 2/5, then what is the exact value of cos 2 theta? If so, then you can apply one of the double angle formulae, ie cos 2 theta = 1-(sin theta)^2                  = 1 - (2/5)^2
Miriam L.
23 October 2013
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