It looks like you're using the Pythagorean theorem to find the hypotenuse $mc$ of a right triangle. According to your equation:

$mc = \sqrt{(10)^2 + (5)^2}$

Let's go through the calculation:

$mc = \sqrt{100 + 25} = \sqrt{125}$

$mc = \sqrt{125} \approx 11.18$

So, the length of $mc$ is approximately 11.18.

Do you need further details on this calculation or would you like to continue with something else?

Here are some related questions that might interest you:

1. How can the Pythagorean theorem be applied in different types of triangles?
2. What happens if the triangle is not a right triangle?
3. How can you use the distance formula (related to the Pythagorean theorem) in geometry?
4. What are the properties of right triangles?
5. How would you solve for the other sides of a triangle if you already know the hypotenuse and one side?

Tip: When you use the Pythagorean theorem, make sure you're working with a right triangle (i.e., a triangle with a 90° angle).