The classic yield sign is an upside-down triangle with two equal sides — traffic engineers chose the shape so drivers recognize it even caked in snow. In plain words, an isosceles triangle has two equal sides and two equal base angles, and its area is still half the base times the height: A = ½ × b × h. A yield-sign-style triangle with a 10-inch base and a 6-inch height covers 30 square inches. The symmetry is the whole point: the altitude from the apex splits the base exactly in half, which is why roof trusses and bridge supports love this shape. Sailboat sails, arrowheads, and pennant flags all borrow the same efficient geometry.

This calculator evaluates the area from base and height. Type the base length into the Variable A box, say 10, and the perpendicular height into the Variable B box, say 6. Read the area from the Result box: 30. Double-check that your height is measured perpendicular to the base — on a skinny triangle the altitude can be surprisingly short.

With the pre-filled defaults — Variable A 10, Variable B 5 — the Isosceles Triangle Calculator returns Result 50.0000. Change any input and those results update instantly, so you can see exactly how each number you enter moves the answer.