Isosceles Triangle Calculator

What this calculator does

An isosceles triangle has two equal sides. Its height to the base also splits the base into two equal parts.

Equal sidesTwo sides have the same length.

HeightThe height splits the base in half.

AnglesThe two base angles are equal.

For classroom work, check the required rounding rules and whether angles are in degrees or radians. This page uses degrees.

Use Pythagorean theorem or law of cosines depending on the triangle case.

Solve right-triangle side and angle questions with a formula explanation.

Find missing angles from sides or from two known angles.

Solve a triangle when all three sides are known.

Use two sides and the included angle.

Solve common oblique triangle cases.