Find cos (2115°) and sin (2115°). Identify the measure of the reference angle.

Cos (2115°) = 1/√2

Sin (2115°) = - 1/√2

Step-by-step explanation:

We have to find the values of Cos (2115°) and Sin (2115°).

Now, 2115° can be written as (23*90° + 45°).

Therefore, the angle 2115° lies in the 4th quadrant where Cos values are positive and Sin values are negative.

Hence, Cos (2115°) = Cos (23*90° + 45°) = Sin 45° {Since 23 is an odd number, so the CosФ sign will be changed to SinФ} = 1/√2 (Answer)

Again, Sin (2115°) = Sin (23*90° + 45°) = - Cos 45° {Since 23 is an odd number, so the SinФ sign will be changed to CosФ} = - 1/√2 (Answer)

Now, the required reference angle is 45°. (Answer)