For 30–60–90, x is the short leg opposite 30°. For 45–45–90, x is either leg.

Can I use a decimal side?

Yes; the ratios work for any positive side length.

30-60-90 and 45-45-90 Triangles Explained

Memorize the two fixed side ratios, then solve any missing side without re-deriving the Pythagorean theorem.

A 45–45–90 triangle has sides x, x, x√2. A 30–60–90 triangle has sides x, x√3, 2x, where x is the short leg.

x : x : x√2

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