Remember that on a right triangle, the trigonometric ratios of a given angle are defined as follows:
[tex]\begin{gathered} \sin \theta=\frac{\text{Side opposed to }\theta}{\text{Hypotenuse}} \\ \cos \theta=\frac{\text{Side adjacent to }\theta}{\text{Hypotenuse}} \\ \tan \theta=\frac{\text{Side opposed to }\theta}{Side\text{ adjacent to }\theta} \end{gathered}[/tex]On the given figure, the side opposite to the angle C has a length of 20, the side adjacent to C has a length of 21, and the hypotenyse has a lenght of 29.
On the other hand, the side opposite to the angle A has a length of 21, the side adjacent to the angle A has a length of 20 and the hypotenuse is the same.
Then:
[tex]\begin{gathered} \sin A=\frac{21}{29} \\ \cos A=\frac{20}{29} \\ \tan A=\frac{21}{20} \\ \sin C=\frac{20}{29} \\ \cos C=\frac{21}{29} \\ \tan C=\frac{20}{21} \end{gathered}[/tex]
