Lesson 10-5 Pages Area: Parallelograms, Triangles, and Trapezoids Lesson Check 10-4

What you will learn! How to find the area of parallelograms, triangles, and trapezoids.

BaseAltitude

What you really need to know! The area A of a parallelogram equals the product of its base b and its height h. A = bh BASE (b) HEIGHT (h)

The area of a parallelogram is the same as the area of a rectangle!

What you really need to know! The area A of a triangle equals half the product of its base b and height h. A = ½bh BASE (b) Height (h)

The area of a triangle is the same as ½ the area of a parallelogram!

What you really need to know! The area A of a trapezoid equals half the product of the height h and the sum of the bases a and b. A = ½ h(a+b) a b h

Notice how the top layer and bottom layer of the trapezoids creates the base of the parallelogram! The area of a trapezoid is the same as ½ the area of a parallelogram!

h h a b

Example 1: Find the area of the parallelogram. A = bh A = 3 x 3 A = 9 m 2

Example 2: Find the area of the parallelogram. A = bh A = 6.2 x 4.3 A = in 2

Example 3: Find the area of the triangle. A = ½ bh A = ½ x 3 x 4 A = 6 m 2

Example 4: Find the area of the triangle. A = ½ bh A = ½ x 3.9 x 6.4 A = ft 2

Example 5: Find the area of the trapezoid.

A = ½ h(a+b) A = ½ x 6(7 ½ + 5 ¼ ) A = 38 ¼ m 2

Example 6: A wall that needs to be painted is 16 feet wide and 9 feet tall. There is a doorway that is 3 feet by 8 feet and a window that is 6 feet by 5 ½ feet. What is the area to be painted?

Area of wall Area of doorway Area of window A = bh A = 16 x 9 A = 144 A = bh A = 3 x 8 A = 24 A = bh A = 6 x 5 ½ A = 33 Area to be painted is: 144 – 24 – 33 = 87 ft 2

Page 523 Guided Practice #’s 3-6

Pages with someone at home and study examples! Read:

Homework: Pages #’s 8-22 even, 24-28, Lesson Check 10-5

Page 749 Lesson 10-5

Lesson Check 10-5