Area of a Trapezoid

Area of a Trapezoid

Lesson Goals

• Determine the area of a trapezoid.

Lesson Standards

• 6.GM.4

  Find the area of complex shapes composed of polygons by composing or decomposing into simple shapes; apply this technique to solve real-world and other mathematical problems.

Mr. McCrory is plowing an area for his popcorn plants. The area measures

 $31\frac{1}{2}yds\ by\ 23\frac{1}{3}yds$  What is the total are of the plot that he will use to grow his popcorn?

• First make the mixed numbers into improper fractions

• Divide down and multiply. 

Multiple Choice

 $31\frac{1}{2}\cdot23\frac{1}{3}$  

What is this changed into improper fractions? 

•  $\frac{31}{2}\cdot\frac{23}{3}$  

•  $\frac{63}{2}\cdot\frac{70}{3}$  

•  $\frac{34}{2}\cdot\frac{27}{3}$  

Finding the area of a trapezoid

• How would you find the area of this shape?

• We will revisit this one later. 

Trapezoid Area Formula

•  $A=\frac{1}{2}h\left(b_1+b_2\right)$  or

•  $A=\frac{h\left(b_1+b_2\right)}{2}$  

Multiple Select

Which two measurements can be used as the base 1 and base 2 for this trapezoid?

• 4m

• 5m

• 8m

Multiple Choice

What is the height of this trapezoid?

• 4m

• 5m

• 8m

Multiple Choice

What is the area of this trapezoid?

• $80m^2$

• $32.5m^2$

• $26m^2$

• $50m^2$

How did you do?

• If you got it wrong, what did you do wrong?

Multiple Choice

What is the area of this trapezoid?

• $22.5in^2$

• $81in^2$

• $45in^2$

• $162in^2$

How did you do?

• If you got it wrong, what did you do wrong?

Review: Trapezoid Area Formula

•  $A=\frac{1}{2}h\left(b_1+b_2\right)$  or

•  $A=\frac{h\left(b_1+b_2\right)}{2}$  

Poll

How would you describe finding the area of trapezoids?

• Easy

• Not bad

• Hard

• Confusing

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