Learn how to calculate the areas of rectangle, triangle, and circle in Excel for a single cell or range of cells usin this formula.

The area of this rectangle is base × height. So you've shown the area of the triangle is half this rectangle = ½ base × height.

We can work out the area of a triangle by working out the area of a rectangle and then dividing it by two. Discover more in this Second Level Bitesize guide.