Question

Special right triangles: what is the value of x? enter your answer in the box.

Answer 1

I think you meant to add more to your question (posting the specific problem).
In general, one special right triangle is the 45°-45°-90° triangle, in which both legs are congruent and the hypotenuse = √2 * the length of the leg. if you happen to not have the length of the leg, the formula for finding the leg is:  leg = hypotenuse / √2

Another special right triangle is the 30°-60°-90° triangle. With this kind of triangle the length of the hypotenuse is twice the length of the shorter leg. The length of the longer leg is √3 times the length of the shorter leg.
hypotenuse = 2 * shorter leg
longer leg = √3 * shorter leg