Jawabanmu

2014-05-19T10:21:54+07:00
Cos 2x= 1-2sin^2x
1-2sin^2x-sin x=0
-2sin^2x-sinx+1=0
(-2sinx+1)(sinx+1)
-2sinx=-1
sinx= 0,5 v sinx=-1

x=30°+k.360 x=270°+k 360
x= 30 x=270
Hp{30,270}