Attempt following question by selecting a choice to answer.
e
Find the value of
(cos4A - sin4A) in terms of
cos 2A.BB eeA.
e cos
22A
B.
e 1 + cos 2A
C.
e 1 - cos 2A
D.
e cos 2A
e
D
Step 1: ( cos4A - sin4A) = (cos2A)2 -(sin2A)2
Step 2: = (cos2A + sin2A)( cos2A - sin2A) = 1 · cos 2A = cos 2A[Use a2 - b2 = (a + b)(a - b) and
cos2A + sin2A = 1 ]