1. **Stating the problem:** We need to match the sides of a right-angled triangle relative to the angle $\theta$. The triangle has a right angle, and $\theta$ is one of the other angles. 2. **Definitions:** - The **hypotenuse** is the side opposite the right angle and is the longest side. - The **opposite side** is the side opposite the angle $\theta$. - The **adjacent side** is the side next to the angle $\theta$ but not the hypotenuse. 3. **Given:** The triangle is right-angled with $\theta$ at the top-right vertex. 4. **Matching sides:** - The **hypotenuse** is the side opposite the right angle (the longest side). - The **opposite side** is the vertical side adjacent to $\theta$ (since $\theta$ is at the top-right vertex, the vertical side opposite $\theta$ is the opposite side). - The **adjacent side** is the horizontal base side next to $\theta$. **Final answer:** - Hypotenuse: side opposite the right angle - Opposite: vertical side opposite $\theta$ - Adjacent: horizontal side next to $\theta$