2Tvwo §6.2 Calculating a side

§6.2 Calculating a side
Do you remember our old, bearded friend from the past?
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Slide 1: Tekstslide
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In deze les zitten 37 slides, met interactieve quizzen en tekstslides.

time-iconLesduur is: 50 min

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§6.2 Calculating a side
Do you remember our old, bearded friend from the past?

Slide 1 - Tekstslide

Slide 2 - Tekstslide

Who is he?

Slide 3 - Woordweb

Solution:
Welcome back to: Pythagoras!
Lived from 570 - 500 before Christ.
Previous slide showed us another picture
of this great Maths chap.
Just a next door guy, isn't he?
 Could've been your neighbour. Or uncle, for that matter...

Slide 4 - Tekstslide

The theorem of Pythagoras
A
is about the sides of a right-angled triangle
B
is used to calculate an unknown angle
C
is invented by Pete Agoras
D
is more than 2500 years old but still going strong

Slide 5 - Quizvraag

Slide 6 - Tekstslide

Slide 7 - Tekstslide

The theorem of Pythagoras...
asks for the use of a very handy scheme!

Slide 8 - Tekstslide

TASK:  +  Make the SKETCH for 8a,
              +  Take a picture and 
              +  Send it in in GC
              +  This is a FOTOVRAAG!        

Slide 9 - Tekstslide

Let's do exercise 8 together,
start doing 8 a), in your Notebook.
MAKE A SKETCH for 8a, and SEND IT IN BY A FOTOVRAAG! (next slide)

Slide 10 - Tekstslide

Sketch triangle KLM with angle K = 90 degrees and
KL = 15 and LM = 20
Take a pic and send it in here!

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0:45

Slide 11 - Open vraag

Here is the sketch:
Of course this triangle could 
also be made upside down.
As long as angle K is 90 degrees!

Slide 12 - Tekstslide

Now think hard about b:
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0:45

Slide 13 - Tekstslide

answer for b:

Slide 14 - Tekstslide

Do c now:
First copy the scheme! Then:
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1:30

Slide 15 - Tekstslide

answer for c:

Slide 16 - Tekstslide

Slide 17 - Tekstslide

Watch Pythagoras, going crazy about his own Theorem!
Where?
Next slide!

Slide 18 - Tekstslide

Slide 19 - Tekstslide

Time to do d:



Do this task in your scheme from c!
Think about the meaning of the words: 'exact length'.

Slide 20 - Tekstslide

answer for d:
'exact' means: not rounded off! 
So write it as a ROOT.


Next slide gives you an important TIP!

Slide 21 - Tekstslide

A TIP for doing 9:
For 9a, b and c you are asked to calculate an unknown side.
USE THE METHOD SHOWN ABOVE EXERCISE.
Watch the next slide!

Slide 22 - Tekstslide

This handy SCHEME you just used for doing exercise 8.
When doing the FOLLOWING TASKS (9  t/m  15)
make a good use of this EVERY TIME!

Slide 23 - Tekstslide

Homework time.
Do §6.2 now, 
+  start with 7, then 9, 10, etcetera
+  make the SCHEME with lengths for every exercise!!
+  remember to place the hypotenuse (=longest side) at the bottom
+ later on this LessonUp is continued
timer
10:00

Slide 24 - Tekstslide

A few fine points from this paragraph follow now!

Slide 25 - Tekstslide

We want to calculate length BD.
What to calculate FIRST?
Give your answer in the next slide.

Slide 26 - Tekstslide

We want to calculate BD.
What to calculate first?

Slide 27 - Woordweb

Solution:   First calculate length CD in right-angled triangle ACD.
Then only calculate length BD in right-angled triangle BCD!

Slide 28 - Tekstslide

One more new thing from §6.2!

Slide 29 - Tekstslide

How (on earth) can you calculate DE or GH?
We do not even have a right-angled triangle! 
(see next slide)

Slide 30 - Tekstslide

Solution: we make a right-angled triangle ourself!!
With that we can make the SCHEME and calculate the unknown side.

Slide 31 - Tekstslide

Next 4 slides are about exercise 15.
I only do those with somebody who like a real Challenge!
So maybe later this lesson you ask me about it,
if you need a little help.

Slide 32 - Tekstslide

Question: Think of a Method to do the exercise, below!

Slide 33 - Tekstslide

The best Method might be:
Making a SKETCH!
How else can we see what to calculate?!
See next slide!

Slide 34 - Tekstslide

Slide 35 - Tekstslide

How to go on?
For every line segment you can now make a 
Pythagoras scheme. 
All lengths will become known.
 Then you can compare them, to find the greatest and the smallest.

Slide 36 - Tekstslide

Homework time again.
Finish as much as you can!

Slide 37 - Tekstslide