The formula for the area of a triangle is one-half the base times the height. In the example provided, the base is 9 units and the height is 20 units, so the area of the triangle is 90 square units.
The formula for the area of a triangle is:
A = 1/2 * b * h
Where:
A is the area of the triangle
b is the base of the triangle
h is the height of the triangle
In the example in the image:
b = 9 units
h = 20 units
Therefore, the area of the triangle is:
A = 1/2 * 9 * 20 = 90 square units