Show worked solution
Worked solution
List the four vertices
We confirm ABCD is a rectangle and find its area and perimeter.
Vector AB
Find the direction and length of side AB.
Length of AB
Side AB is 5 units long.
Vector BC
Find the direction and length of side BC.
Length of BC
Side BC is 9 units long.
Check the corner is a right angle
The two side vectors are perpendicular, confirming a rectangle.
Check the fourth vertex
D completes the rectangle as given.
Write the area formula
For a rectangle, multiply the two different side lengths.
Substitute the side lengths
Use AB and BC as the length and width.
Work out the area
The area is 45 square units.
Write the perimeter formula
Add the four sides.
Work out the perimeter
The perimeter is 28 units.
Sketch check
The plotted points form the expected axis-aligned rectangle.
Common mistake
Area multiplies the sides; adding them gives half the perimeter, not the area.
State the results
The rectangle has area 45 square units and perimeter 28 units.