Input (grade 9): Using the unit circle, two identities can be found: cos (t) = cos (2 k + t) and sin (t) = sin (2 k + t) for any integer t.
Output (grade 2): Using the unit circle, two identities can be found: cos (t) = cos (2 \* 3.14 k + t) and sin (t) = sin (2 \* 3.14 k + t) for any integer t.