Solve for X on a triangle with three sides, 1 side is 39 cm, the second side is 80 cm and the third side is x, calculate x using the Pythagorean Theorem

1 answer

To use the Pythagorean Theorem, we first need to determine if the triangle described is a right triangle. The Pythagorean Theorem states that for a right triangle with legs \(a\) and \(b\), and hypotenuse \(c\), the relationship is given by:

\[ c^2 = a^2 + b^2 \]

In your case, you provide three sides: 39 cm, 80 cm, and \(x\). We need to check if \(x\) can be the hypotenuse or one of the legs of a right triangle.

Let's first calculate \(x\) assuming \(x\) is the hypotenuse. If \(x\) is the hypotenuse, then:

\[ x^2 = 39^2 + 80^2 \]

Calculating the squares:

\[ 39^2 = 1521 \] \[ 80^2 = 6400 \]

Now substituting these values back into the equation:

\[ x^2 = 1521 + 6400 \] \[ x^2 = 7921 \]

Taking the square root of both sides gives:

\[ x = \sqrt{7921} \] \[ x = 89 \]

Now, let's check if \(x\) could be one of the legs instead. We can assume 80 cm is the hypotenuse:

\[ 80^2 = 39^2 + x^2 \]

Calculating the squares again:

\[ 6400 = 1521 + x^2 \]

Now, rearranging the equation:

\[ x^2 = 6400 - 1521 \] \[ x^2 = 4879 \]

Taking the square root of both sides gives:

\[ x = \sqrt{4879} \approx 69.9 \]

So, we have two possible scenarios for \(x\):

  1. If \(x\) is the hypotenuse: \(x = 89\) cm
  2. If \(x\) is one of the legs: \(x \approx 69.9\) cm

In conclusion, \(x\) can be either \(89\) cm (if it is the hypotenuse) or approximately \(69.9\) cm (if it is one of the legs).