Řešení - Trigonometry

The cotangent of an angle is equal to the cosine of the angle divided by the sine of the angle.

$$\cot \left(90°\right)=\frac{\cos \left(90°\right)}{\sin \left(90°\right)}$$

Computing the cosine of 90 degrees.

$$\frac{\cos \left(90°\right)}{\sin \left(90°\right)}=\frac{0}{\sin \left(90°\right)}$$

Computing the sine of 90 degrees.

$$\frac{0}{\sin \left(90°\right)}=\frac{0}{1}$$

The fraction equals zero if its numerator is zero.

$$\frac{0}{1}=0$$