Unit 4 Chapter 6 Section 3 Area of a Triangle.notebook
March 02, 2015
Bellringer:
Find the unknown measures for each rectangle.
1) l = w = 4.2 m
A = 37.8 m2
P = 2) l = 8 in
w = A = P = 50 in
Unit 4 Chapter 6 Section 3 Area of a Triangle.notebook
March 02, 2015
Unit 4
Chapter 6 Section 3
Area of a Triangle
Objective: To find the area of a triangle and to relate side lengths and area
Take a rectangle
h
Break the rectangle
into two triangles
Draw one diagonal
h
h
b
b
b
A = bh
A=
A = bh
Triangle: three sided polygon
h
b = base of triangle
h = height of triangle
b
h
b
h
b
Area of a Triangle: A = 1 bh
2
Unit 4 Chapter 6 Section 3 Area of a Triangle.notebook
March 02, 2015
Examples:
Finding the Area of a Triangle
1) Find the area and perimeter of each triangle
b)
13 6.5 ft
6.5 ft
m
a)
9 m
24
5 ft
m
13 ft
area = area = perimeter = perimeter = 2) Find area of each triangle.
a) b = 12 m
h = 17 m
b) b = 6.2 ft
h = 2.5 ft
12 m
Unit 4 Chapter 6 Section 3 Area of a Triangle.notebook
March 02, 2015
Relating Perimeter and Area
3) A quilt has a design of small and large triangles. A small triangle is shown below. A large triangle has the same shape, but the sides are twice as long as the sides in the small triangle. How does the area of the large triangle compare to that area of the small triangle?
4.7 in
3.1 in
3.4 in
4) What is the unknown side length of the triangle?
15 cm
Area = 54 cm2
12 cm
5) The perimeter of this triangle is 31.4 ft. What is its area?
13.4 ft
12 ft
Unit 4 Chapter 6 Section 3 Area of a Triangle.notebook
March 02, 2015
Challenge
1) Jake has a garden shaped like a parallelogram. Its base is 6 m and its height is 4.5 m. If he plants carrots in half of his garden, what is the area of the carrot patch?
2 . What is 2) The area of an isosceles right triangle is 121 ft
the approximate length of each of the two equal sides?
Unit 4 Chapter 6 Section 3 Area of a Triangle.notebook
Homework
Practice Worksheet 6­3
March 02, 2015