If cosx=(1/2 + (2^1/2)/2)^1/2 and sinx=-(1/2 - (2^1/2)/2)^1/2 0<x<2pi. It follows that 2x=kpi. The value of k is:
3 answers
k = 4
sorry i made a mistake..... Correction cosx=(1/2 + (2^1/2)/4)^1/2 and sinx=(1/2 + (2^1/2)/4)^1/2
since cosx = √(1 + 1/√2)/2) cos2x = 1/√2, so 2x = π/4 or 7π/4
since cosx>0 and sinx<0 only in QIV,
3π/2 < x < 2π
that means 3π < 2x < 4π
Looks like k = 7/4
since cosx>0 and sinx<0 only in QIV,
3π/2 < x < 2π
that means 3π < 2x < 4π
Looks like k = 7/4