The image shows a right triangle where one leg is 21 units, the other leg is 10 units, and $x$ is the angle between the 21-unit leg and the hypotenuse.

To find the angle $x$, we can use trigonometric functions. Since we have the opposite side (10 units) and the adjacent side (21 units), we will use the tangent function:

$\tan(x) = \frac{\text{opposite}}{\text{adjacent}} = \frac{10}{21}$

Now, solve for $x$:

$x = \tan^{-1}\left(\frac{10}{21}\right)$

Using a calculator to find the inverse tangent:

$x \approx \tan^{-1}(0.476) \approx 25.29^\circ$

So, the value of $x$ is approximately $25.29^\circ$.

Would you like more details, or do you have any questions?

Here are five related questions:

1. How would the calculation change if the hypotenuse were known instead of both legs?
2. Can you find the other angle in the triangle?
3. How do we calculate the hypotenuse length using the Pythagorean theorem in this case?
4. What are the values of sine and cosine for the angle $x$?
5. How do we convert the angle $x$ from degrees to radians?

Tip: Always ensure your calculator is set to the correct mode (degrees or radians) when working with trigonometric functions.