The area of a sail is 40 1/2 square feet. the base and the height of the sail are equal. what is the height of the sail (in feet)?

Assuming a sail is a triangle shape, Area of a triangle is (Base x Height)/2
Set this equal to the area given:
40.5 = (Base * Height)/2                    multiply 2 to both sides to cancel the 2 out
81= Base * Height              Since base and height are equal as the equation says you can represent them as x
81 = x * x      x times x is x squared
81 = x²        square root both sides to get x by itself
√81 = √x²
9 = x This means both the base and the height are each 9 feet long

Arhombus is a quadrilateral.