1. 11.1 Area of Parallelograms & Triangles
HW pg. 723 #4­26 evens 1
March 24, 2014
11.1 Areas of Triangles & Parallelograms
Objectives:
1. To develop the concept of area.
2. Apply area formulas to solve problems.
Formula for:
Area of a Rectangle: A = bh
The base and height are
always perpendicular to
each other.
What is area?
Rules for Using Formulas:
1. Always state the formula you are using first!
2. Identify the knowns & unknowns for each variable in the formula.
3. Plug the knowns into the equation.
4. Solve for the unknown using algebra.
5. Be sure to include a label with your answer.
A = _____
10.5m22m
Find the area of the rectangle:
6m
12m
20m
Area of a Parallelogram: A = bh
The altitude will be
perpendicular to the base.
A = _____
Find the area of the parallelogram:
Area of a Triangle = 1/2bh
h
b
Find perimeter and area of the triangle.
8
17
10
21
P = 48 units
A = 84 units2
Base & height are always
perpendicular to each other!
Triangles can have multiple appearances:
Find the height of the parallelogram.
x
20 m
Area = 100 m2
Find the area of the rectangle.
18 m
y
Perimeter = 50 m

2. 11.1 Area of Parallelograms & Triangles
HW pg. 723 #4­26 evens 2
March 24, 2014
Find the area and perimeter of the shaded region.
18m
15m
10m
9m 8cm
6cm
3cm
1cm
5cm
11cm
P = 66 m
A = 222 m2
P = 38 cm
A = 77 cm2
HW:
11.1 pg. 723
#4-26 evens