Attempt following question by selecting a choice to answer.
D
Using the half-angle formula, identify a formula for
cos (A4).BBB DDDA.
D 2
cos2A2 - 1
B.
D ±
1 - cosA22C.
D 12 cosA2D.
D ±
1 + cosA22
DD
D
Step 1: cos (A4) = ±1 + cosA22[Using cosx2 = ±1 + cos x2; Substitute x = A2.]