Assuming both the Adjacent and the Opposite side of the triangle is 6, you’ll need to square both the sides and add them.
Step 1. Square both known sides.
6^2+6^2
Step 2. Simplify.
36+36=72
Step 3. Square root your final answer to find the diagonal or hypotenuse.
Square root of 72 is 8.49.
Answer: 8.5 for the length of the diagonal.
-If one of the sides isn’t 6, repeat the steps above and plug in the different number