We have two responses for you.

Hi Lee,

When we are dealing with right angled triangles we have Pythagoras' theorem to make life simple.
If we read your question carefully they are asking us for the "long side of a right angle triangle", well the longest side of a right angled triangle is always the hypotenuse.
using the theorem a² + b² = c² where a and b represent the sides of the triangle and c is the hypotenuse. Since you know the other two sides, you can plug in your values and solve for c! (², represents squared. So we have "a squared" + "b squared" = "c squared")

good luck,

Jaymi

Hi Lee.

Try using the Pythagorean Theorem. It says that in any right
triangle, the long side (called the "hypotenuse") is related to the
other two sides (called the "legs") this way:

h² = a² + b²

where h is the length of the hypotenuse and a and b are the lengths of
the sides.

So you need to solve this for your question:

h² = 47² + 56²

Hope this helps,
Stephen La Rocque.