## Trigonometry (11th Edition) Clone

In letter D, the angle $140^{\circ}$ has no reference angle that is a special angle.
All the trigonometric functions in A, B, and C can be solved using reference angles that are special. ($30^{\circ}, 45^{\circ}, 60^{\circ}, 90^{\circ}$) But, in letter D, the angle $140^{\circ}$ has no reference angle that is a special angle.