A $30\text{-}60\text{-}90$ triangle is a special type of a right triangle that has two acute angles measuring $30^{\circ }$ and $60^{\circ }$ in addition to the right angle.

If the shorter leg in a $30\text{-}60\text{-}90$ triangle has the length $\ell ,$ the longer leg will have the length $\sqrt{3}\ell ,$ and the length of the hypotenuse will be $2\ell .$

These relations can be deducted from the trigonometric ratios and the known trigonometric values of the notable angles.