Find a positive coterminal angle of θ=π/4.

7π/4

9π/4

11π/4

13π/4

Find a negative coterminal angle of θ=π/4.

-3π/4

-5π/4

-7π/4

-11π/4

To find a positive coterminal angle of θ=π/4, add 2π (after going a full circle counterclockwise around, the angle is the same)

π/4+2π=9π/4.

To find a negative coterminal angle of θ=π/4, subtract 2π (after going a full circle clockwise around, the angle is the same)

π/4-2π=-7π/4.