Cot (15 degrees) find the two common angles that differ by 15 degrees. rewrite this problem as the cotangent of a difference of those two angles.

We have to write 15 degree as the difference of two angles.

And

Now we have to use the formula of cotangent of a difference of those two angles.

And the formula is

THerefore,

And that's the required expressions .

step-by-step explanation:

descending order means to order the polynomials from the term with the largest exponent to the term with the smallest exponent.  

therefore, the correct answer is d.