verdubbelingsf

sin(2A) = 2sin(A)cos(A)
cos(2A) = cos^2(A) - sin^2(A)
cos(2A) = 2cos^2(A) - 1
cos(2A) = 1 - 2sin^2(A)
sin(2A) = 2sin(A
)cos(A)
cos(2A) = cos^2(
A) - sin^2(A)
cos(2A) = 2cos^2
(A) - 1
cos(2A) = 1 - 2s
in^2(A)