Jika s = 1+½sin2x + ¼sin²2x+⅛sin³2x+ ....., maka

s = 1+½sin2x + ¼sin²2x+⅛sin³2x+ .....,
barisan geomemtri

s = a/(1-r)
a= 1
r = U2/U1
r = 1/2.sin2x/1
r = 1/2.sin2x

s = a/(1-r)
s = 1/(1 - 1/2.sin2x)
s = 1/(2/2 - 1/2.sin2x)
s = 1/((2-sin2x)/2)
s = 2/(2-sin2x)

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