Which statement is true?
A. cosine squared 47 degrees equals Start Fraction 1 plus cosine 94 degrees over 2 End Fraction
B. cosine left parenthesis Start Fraction pi over 4 End Fraction right parenthesis equals plus or minus Start Root Start Fraction 1 plus cosine left parenthesis Start Fraction pi over 8 End Fraction right parenthesis over 2 End Fraction End Root
C. tangent 34 degrees equals Start Fraction 2 tangent 68 degrees over 1 minus tangent squared 68 degrees End Fraction
D. sine left parenthesis Start Fraction pi over 6 End Fraction right parenthesis equals cosine squared left parenthesis left parenthesis Start Fraction pi over 12 End Fraction minus sine squared left parenthesis Start Fraction pi over 12 End Fraction