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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This lesson contains 36 slides, with interactive quizzes and text slides.

time-iconLesson duration is: 50 min

Items in this lesson

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

Slide 1 - Slide

Slide 2 - Slide

Who is he?

Slide 3 - Mind map

Welcome back to: Pythagoras!
Lived from 570 - 500 before Christ.
Previous slide showed us another picture
of this great Maths chap.
Not just a next door guy, isn't he?

Slide 4 - Slide

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

Slide 5 - Quiz

Slide 6 - Slide

Slide 7 - Slide

Slide 8 - Slide

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

Slide 9 - Slide

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

Slide 10 - Slide

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 11 - Slide

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


Slide 12 - Open question

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

Slide 13 - Slide

Now think hard about b:

Slide 14 - Slide

answer for b:

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Do c now:
First copy the scheme! Then:

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answer for c:

Slide 17 - Slide

Slide 18 - Slide

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

Slide 19 - Slide

Slide 20 - Slide

Time to do d:

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

Slide 21 - Slide

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

Next slide gives you an important TIP!

Slide 22 - Slide

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

Slide 23 - Slide

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 24 - Slide

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

Slide 25 - Slide

A few fine points from this paragraph follow now!

Slide 26 - Slide

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

Slide 27 - Slide

We want to calculate BD.
What to calculate first?

Slide 28 - Mind map

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

Slide 29 - Slide

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

Slide 30 - Slide

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

Slide 31 - Slide

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

Slide 32 - Slide

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

Slide 33 - Slide

Slide 34 - Slide

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 35 - Slide

Homework time again.
Finish as much as you can!

Slide 36 - Slide