Use the Pythagorean theorem to find the missing hypotenuse.

Triangle with length of 5cm and height of 12cm

To find the missing hypotenuse, we can use the Pythagorean theorem, which states that in a right-angled triangle, the square of the length of the hypotenuse (the side opposite the right angle) is equal to the sum of the squares of the other two sides.

Let's denote the length of the hypotenuse as "c", and the other two sides as "a" and "b". In this case, the length is 12 cm, so we have:

c^2 = a^2 + b^2

Since we know the length (a) and height (b) of the triangle, we can substitute those values:

c^2 = 5^2 + 12^2
c^2 = 25 + 144
c^2 = 169

To find the value of c, we need to take the square root of both sides of the equation:

c = √169
c = 13 cm

Therefore, the length of the missing hypotenuse is 13 cm.