trig
posted by Jom on .
find the values of x between 0 and 2 pi where the tangent line to the graph of y = sinxcosx is horizontal

Hmmmm. Wondering if you are taking calculus.
Calculus
y=sinxcosx
y'=0=cos^2xsin^2x
cos^2x=sin^2x
tan^2 x=1
tanx= +1
which occurs at increments of 45 degrees
x= +PI/4, PI+Pi/4
check that