2Tvwo §8.3 Trapezium

§8.3 Trapezium
Learning goals:   
1. what is a trapezium?
2. how to calculate the area of a trapezium?

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WiskundeMiddelbare schoolhavo, vwoLeerjaar 2

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§8.3 Trapezium
Learning goals:   
1. what is a trapezium?
2. how to calculate the area of a trapezium?

Slide 1 - Diapositive

We are going to do this Task right now. So:
1. Open your Notebook and
2. take a pen(cil) from your pencil case

Slide 2 - Diapositive

Make this task in your Notebook.
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1:00

Slide 3 - Diapositive

SOLUTION:

Slide 4 - Diapositive

Make 17b in your Notebook now.
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1:00

Slide 5 - Diapositive

SOLUTION:

Slide 6 - Diapositive

Make 17c in your Notebook now.
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0:25

Slide 7 - Diapositive

SOLUTION 17c:

Slide 8 - Diapositive

Let's look at 17b once more. Here the Area of the 
Parallelogram is calculated as the Addition of the Areas of the two Triangles:
QUESTION:
Isn't it possible to do this quicker, 
as follows:
Area PQRS = 1/2 x 4 x (9 + 10) ?! Check this.
Answer in the next slide!

Slide 9 - Diapositive

Is it possible?
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0:25
A
yes
B
no
C
it depends

Slide 10 - Quiz

 Areas of the two Triangles:
Yes it is possible to do this quicker!
as follows:
Area PQRS = 1/2 x 4 x (9 + 10) = 1/2 x 4 x 19 = 38
This result is the same as you see above:
Area PQRS = 18 + 20 = 38
Next slide summarizes this in a Theory.

Slide 11 - Diapositive

From now on we will not divide up the Trapezium in two Triangles any more.
So the picture on the right will be used in the exercises.

Slide 12 - Diapositive

Slide 13 - Diapositive

Which is the ISOSCELES triangle?

Slide 14 - Diapositive

What colour does the ISOSCELES
triangle have?
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A
green
B
blue
C
pink
D
purple

Slide 15 - Quiz

The ISOSCELES triangle is the PINK one!
It has two equal sides. This is important in exercise 20.

Slide 16 - Diapositive

Homework:
Choose from these options:
-  19, 20, 21, C5, C6
Later a little more information is given in this Lesson Up!

Slide 17 - Diapositive

When I see this exercise, it gets dark before my eyes...
All this information is ABACADABRA to me.
What is THE WAY to go from darkness to light?
Think about this.

Slide 18 - Diapositive

SOLUTION:
Make a SKETCH will help you out!! Look:


Slide 19 - Diapositive

The last TIP:
Sometimes you can't get around
using the THEOREM of PYTHAGORAS!
Like here, because you need to know
the height of the parallelogram!


Slide 20 - Diapositive

Homework:
§8.3:       19, 20, 21, C5, C6

Slide 21 - Diapositive

Slide 22 - Diapositive