Question 444008
 sin(x)*tan(x)=(1-cos^2(x))/cos(x)
..
For (0 <= x <= 90º)
sinxtanx=(1-cosx)/cosx
sinx(sinx/cosx)=(1-cosx)/cosx
cancel out cosx
sin^2x=1-cosx
1-cos^2x=1-cosx
cos^2x-cosx=0
cosx(cosx-1)=0
cosx=0
x=90º
cosx-1=0
cosx=1
x=0