1. Unifying Themes in Area Formulas

2. LENGTH × WIDTH

3. AREAS of Rectangles, Triangles, and Trapezoids
Average width X
height
𝑎+𝑏 2 ℎ h b

4. AREAS of Rectangles, Triangles, and Trapezoidsb
Average width X
height
𝑏+𝑏 2 ℎ=𝑏ℎ h b

5. AREAS of Parallelograms, Triangles, and Trapezoidsb
Average width X
height
𝑏+𝑏 2 ℎ=𝑏ℎ h b

6. AREAS of Rectangles, Triangles, and Trapezoids
Average width X
height
𝑏+0 2 ℎ= 𝑏ℎ 2 h b

7. Ellipses and Circles r
𝐴𝑟𝑒𝑎=𝜋 ∙𝑟 ∙𝑟=𝜋 𝑟 2 r

8. Ellipses and Circles b
𝐴𝑅𝐸𝐴=
𝜋 ∙𝑎 ∙𝑏=𝜋𝑎𝑏 a

9. Ellipses and Circles r
Perimeter=2𝜋𝑟 r

10. Ellipses and Circles Perimeter ≈ 2𝜋 𝑎 2 + 𝑏 2 2 b a
2𝜋 𝑎 2 + 𝑏 2 2 b
This works exactly when
a=b=r on a
circle a
This is not exactly correct!
You need
Calculus to
do this correctly!