Given that the problem does not specify if y is <span>opposite, adjacent or hypotenuse side, I will provide two solutions to this problem.
Case 1. Y is the hypotenuse side. (See figure 1)
According to the Pythagorean Theorem, for a right triangle, it is true that:
</span>
<span>
being c the hypotenuse side and a and b the opposite and adjacent side respectively. So, for the figure 1 it is true that:
</span><span>
z = a = 15cm
x = b = 9cm
y = c = ?
</span>
∴
Case 2. Y is the opposite side (The same happens as if it were the adjacent side). (See figure 2)
From the equation:
For the figure:
y = a = ?
x = b = 9cm
z = c = 15cm
We need to isolate a, so:
∴
Case 1. Y is the hypotenuse side. (See figure 1)
According to the Pythagorean Theorem, for a right triangle, it is true that:
</span>
<span>
being c the hypotenuse side and a and b the opposite and adjacent side respectively. So, for the figure 1 it is true that:
</span><span>
z = a = 15cm
x = b = 9cm
y = c = ?
</span>
∴
Case 2. Y is the opposite side (The same happens as if it were the adjacent side). (See figure 2)
From the equation:
For the figure:
y = a = ?
x = b = 9cm
z = c = 15cm
We need to isolate a, so:
∴
