The acre is a measurement used to quantify large areas, often tracts of land. The word "acre" comes from old Greek and Latin words meaning "field." The more acres a lot takes up, the larger the lot. If you have a triangular lot, you need to know the base and height dimensions of the lot to figure the acreage. Knowing the correct acreage helps you to accurately price a piece of property.
Pick one side of the triangle to use as the base and measure the length in feet. It does not matter which side of the triangle that you use.
Measure the perpendicular distance from the base of the triangle to the top of the triangle in feet. This is the height of the triangle.
Multiply 1/2 times the base times the height. For example, if you have a length of 350 feet and a height of 600 feet, multiply 350 by 600 by 1/2 to get 105,000 square feet.
Divide the number of square feet by 43,560 to convert to acres. In this example, divide 105,000 square feet by 43,560 to get 2.41 acres.