Review the proof. A 2-column table with 8 rows. Column 1 is labeled Step with entries 1, 2, 3, 4, 5, 6, 7, 8. Column 2 is labeled Statement with entries cosine (2 x) = 1 minus 2 sine squared (x), let 2 x = theta, then x = StartFraction theta Over 2 EndFraction, cosine (theta) = 1 minus 2 sine squared (StartFraction theta Over 2 EndFraction), negative 1 + cosine (theta) = negative 2 sine squared (StartFraction theta Over 2 EndFraction), 1 + cosine (theta) = 2 sine squared (StartFraction theta Over 2 EndFraction), StartFraction 1 minus cosine (theta) Over 2 EndFraction = sine squared (StartFraction theta Over 2 EndFraction), sine (StartFraction theta Over 2 EndFraction) = plus-or-minus StartRoot StartFraction 1 minus cosine (theta) Over 2 EndFraction EndRoot.

Which step contains an error?

step 2
step 4
step 6
step 8