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)

No

Step-by-step explanation:

In a right angle triangle, based on Pythagoras theorem, the sum of the squares of the adjacent and opposite sides must equal to the square of the hypotenuse.

     The hypotenuse is the side with the longest length:

            H²  = O²  + A²

 if from the given lengths;

           H = 11, O = 9 and A = 6

Let us see if this is true;

          H²  = 9² + 6²

          H²  = 81 + 36

         H² = 117

But H², 11²  = 121 and this is not true

 The triangle is not a right angled one.