Choose the mode that matches the values you have, enter only positive measurements, and let the calculator derive the rest.

1. Pick the input mode.
2. Enter the required values.
3. Read the area, perimeter, and angle values from the result card.

With equal sides 5 and base 6, the area is 12, the perimeter is 16, and the base angles are 36.869898°.

With base 6 and height 4, the equal sides are 5.

The old calculate-button workflow has been replaced with live validation so the displayed geometry always matches the current inputs.

Impossible base and side combinations are rejected before any square root is evaluated.