Quote: Given that cos2x= 7 over 9 0<x<90, what is the value of sinx ?
cos(2x) =
1 - 2sin
2(x) = 7/9
2sin
2(x) = 2/9
sin
2(x) =1/9
sin(x) = +/- 1/3
x = arcsin(1/3) or x=arcsin(-1/3) BUT, arcsin(-1/3) is outside of [0,90] so we disregard it and thus
x = arcsin(1/3)