Since 0<t<π/2, then sin(t)>0, cos(t)>0, sec(t)=1/cos(t)>0, and cot(t)=1/tan(t)>0. Always helps to draw right triangles with labelled sides for these kinds of problems.
tan(t) = Opposite/Adjacent = 3/4
sin(t) = Opposite/Hypotenuse = 3/√(32+42) = 3/5
cos(t) = Adjacent/Hypotenuse = 4/5
sec(t) = Hypotenuse/Adjacent = 5/4
cot(t) = Adjacent/Opposite = 4/3
Therefore, sin(t)=3/5, cos(t)=4/5, sec(t)=5/4, and cot(t)=4/3 given 0<t<π/2.
Hope this helped!