The Solution:
Given the right-angled triangle below:
We are asked to find the cosine of angle R.
Using the Trigonometrical Ratio below:
[tex]\begin{gathered} \cos R=\frac{\text{adjacent}}{\text{hypotenuse}}=\frac{RT}{RS}=\frac{6}{10}=\frac{3}{5} \\ \end{gathered}[/tex]
Thus, the cosine of angle R is 3/5.
Therefore, the correct answer is 3/5
