The expression sec x +1 was simplified with the following steps: tan x Step 1: Sec x tan x tan x Step 2: cos x tan x tan x Step 3: Cos x sin x sin x COS X COs X Step 4: - 1 sin x sin x cosx Step 5: cscx +- sin x COS X Step 6: csc x + tanx Which identity/formula was used to simplify from step 4 to step 5? O Sum formula O Double-angle formula O Reciprocal identity O Quotient identity