How do you solve sqrt2sin2x=12sin2x=1 between the interval 0<=x<=2pi0x2π?

1 Answer

We have that

sqrt2 sin2x=1=>sin2x=1/sqrt2=>sin2x=sqrt2/2=> sin2x=sin(pi/4)2sin2x=1sin2x=12sin2x=22sin2x=sin(π4)

Hence from the last relation we get

2x=2kpi+pi/4=>x=kpi+pi/82x=2kπ+π4x=kπ+π8

or

2x=2kpi+pi-pi/4=>2x=2kpi+3pi/4=>x=kpi+3pi/82x=2kπ+ππ42x=2kπ+3π4x=kπ+3π8

Because 0<=x<=2pi0x2π acceptable solutions are

x_1=pi/8,x_2=9pi/8,x_3=3pi/8,x_4=11pi/8x1=π8,x2=9π8,x3=3π8,x4=11π8