📐 Isosceles Triangle Calculator

Calculate sides, area and angles of an isosceles triangle.

Equal sides length (a) Base length (b)

What is an Isosceles Triangle?

A triangle with two equal sides. The angles opposite the equal sides (base angles) are also equal. Apex angle (α) and base angle (β): α + 2β = 180°

Height Formula

h = √(a² − (b/2)²)

a: 등변(같은 변의 길이), b: 밑변

Area Formula

S = (b × h) / 2

Apex Angle

α = 2 × arcsin(b / (2a))

Base Angle

β = (180° − α) / 2

Perimeter

L = 2a + b

Properties of an Isosceles Triangle

The perpendicular from the apex angle to the base bisects the base perpendicularly. That is, the foot of the perpendicular is the midpoint of the base.