Question
If cos4 B - sin4 B =
src='https://static.ixambee.com/public/images/quesimg/Question Bank/Quantitative Aptitude/Trigonometry/86662_5358143.gif'> , then the value of 2 cos2 B - 1 isSolution
cos4 B - sin4 B = 
(cos2 B + sin2 B)(cos2 B - sin2 B) = (cos2Â B - sin2Â B) = cos2Â BÂ - (1-cos2Â B) = 2 cos2Â B-1 =
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