In a 45-45-90 triangle the legs are equal and the hypotenuse is a leg times √2. Sides are x, x, x√2. Leg 7 means hypotenuse 7√2. Special right triangles as a set are in Pythagorean theorem and special right triangles.
Both acute angles are 45
An isosceles right triangle is always 45-45-90. If you are given the hypotenuse, divide by √2 to get a leg. A square cut along a diagonal makes two of these. Do not use the 30-60-90 list here.
30-60-90 is the other frozen ratio, in 30-60-90 triangles. Two equal sides and two equal base angles more generally are in isosceles and equilateral triangles. Formulas as a set are in ACT Math formulas.
The bottom line
Legs equal. Hypotenuse is a leg times √2.
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