Which one of the following statements is TRUE?

The double-angle form cos2A = 2co$s^2$$A-1$ with $A=30$° gives 2$(\surd 3/2{)}^2-1=2$(3/4) − 1 = 1/2 = cos60°, so that statement is true. Sine, tangent and the double angle are not additive: for example sin(30° + 60°) = 1 while sin30° + sin60° ≈ 1.366.