Since the angle at which a tangent of a circle meets a radius of the circle is 90 degrees, the triangle ACD is a right triangle and we can apply the Pythagorean theorem to find the length of side DA, which is the hypothenus, as follows:


![\begin{gathered} DA^2=15^2+8^2=225+64=289 \\ DA=\sqrt[]{289}=17 \end{gathered}](https://img.qammunity.org/2023/formulas/mathematics/college/n8vzgbkwzqz8ki9icnoggq7hriank8ex7u.png)
Thus:

Now, to find the value of DE, we observe that AE is the radius of the circle which we have been given to be 8.
Thus, we have that:


Therefore:
