Download Hffl Areas of Triangles and Parallelograms

Geometry Lesson 11-1: Areas of Triangles and Parallelograms
Learning Target: By the end of today’s lesson, we will be able to find areas of triangles and parallelograms.
Bases of a parallelogram: ____________________________________________________________________
Height of a parallelogram: ___________________________________________________________________
Postulate 24: Area of a Square Postulate
The area of a square is the _______________ of the length of its side.
Postulate 25: Area Congruence Postulate
If two polygons are ____________________, then they have the same area.
Postulate 26: Area Addition Postulate
The area of a region is the ______ of the areas of its nonoverlapping parts.
Theorem 11.1: Area of a Rectangle
The area of a rectangle is the product of its __________ and __________.
Theorem 11.2: Area of a Parallelogram
The area of a parallelogram is the product of a __________ and its corresponding __________.
Theorem 11.3: Area of a Triangle
The area of a triangle is __________ the product of a __________ and its corresponding __________.
Example 1: Find the area of each polygon.
a.)
b.)
c.)
Example 2: The base of a triangle is four times its height. The area of the triangle is 50 square inches.
Find the base and height.
Example 3: A parallelogram has an area of 133 square feet and a height of 19 feet.
What is the length of the base?
Example 4: A robotic vacuum cleaner can clean 2 square meters of carpet in 8 minutes.
How long does it take for it to clean a carpet covering a room with the dimensions shown below?
Area of a Triangle: SAS Formula
In a triangle where a and b are known sides and C is the measure of the included angle,
Area =
1
ab  SinC
2
Example 5: Find the area of each triangle.
a.)
b.)
c.)