cos 8x − 1
is gelijk aan
A.  − 2 sin ² 4x
B.  4 sin ² x
C.  − 8 sin ² x
D.  8 sin ² x
E.  2 sin ² 4x
A    B    C    D    E

[ 5-4972 - op net sinds 1.4.2020-(E)-8.11.2023 ]

Translation in   E N G L I S H

cos 8x − 1
is equal to
A.   − 2 sin ² 4x
B.   4 sin ² x
C.   − 8 sin ² x
D.   8 sin ² x
E.   2 sin ² 4x

Oplossing - Solution

1ste manier : met de formule 1 − cos 2α = 2.sin² α
cos 2α − 1 = − 2.sin² α
cos 8x − 1 = − 2.sin² 4x
2de manier :
cos 8x − 1 = cos²4x − sin²4x − 1 = − sin²4x − sin²4x = − 2sin²4x
gricha