Presentation on theme: "Area Area problems involve finding the surface area for a two-dimensional figure."— Presentation transcript:
Area Area problems involve finding the surface area for a two-dimensional figure.
Area Area problems involve finding the surface area for two-dimensional figures. What is surface area: it is the amount of space on the front of a two-dimensional figure. Suppose you were painting a wall, you would need to know the surface area so you would know how much paint to buy.
Two-Dimensional Two dimensional means a shape has only two measurements: either length and width, base and height, etc. Example: the Area formula for a rectangle is: A = lw or Area = length times width You used two dimensions to calculate with. What dimension you don’t calculate is depth.
What Shapes? We will be calculating area for: Squares Rectangles Rhombus Parallelogram Trapezoid Triangle Circle
Square The area formula for a square is: s² That is side squared. Remember all sides of a square are equal Example: the area for a square with sides of 5 inches: A = 5² or 25 inches²
Rectangle The area formula for a rectangle is: A = lw That means A = length times width Example: a rectangle with a length of 20 feet and a width of 10 feet: A = or 200 ft.²
Rhombus & Parallelogram They have the same area formula: A = bh or Area = base times the height The base and height will be marked so you can calculate very easily. Example: a parallelogram with a base of 10 cm and a height of 4 cm = A = 4 10 = 40cm²
Trapezoid The area formula for a trapezoid is the most difficult: ½h(b₁ + b₂) That is half (.5) the height times the sum of the top base and the bottom base.
Circle Area formula for a circle: A = πr² Remember: pi = 3.14 (π) r = radius² Example: circle with a radius of 3 inches: ² = or in.²
Triangle Area formula for a triangle: A = ½bh or Area = one half (.5) the base times the height Example: a triangle with a base of 12 mm and a height of 10 mm = = 60mm²
Area Is it a useful problem especially if you are: – In the field of construction – In the field of roofing – In the field of plastering or painting – In the field of sewing, designing