Answer:
A triangle with angles:
"45°, 45°, 90°"
Is a triangle rectangle, with two catheti of equal length.
Now, there is a lot of problems that you can solve with this:
"Suppose that you want to find the height at which you need to attach a wire in a tree, such that the distance between the tree and the ground is 18ft, and the distance between the base of the tree and the two points where the wire is fixed is exactly the same"
Well, here we have a triangle rectangle with a hypotenuse of 18 ft, with cathetus of equal length (the catheti are the tree and the distance between the base of the tree and the point where the wire is attached at the ground)
And because the catheti are equal, then the angles are 45°, 45° and 90°.
