2Tvwo §6.2 Calculating a side

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• Leerjaar 2

§6.2 Calculating a side

Do you remember our old, bearded friend from the past?

Who is he?

§6.2 Calculating a side

Welcome back to: Pythagoras!

Next slide shows us another picture

of this great Maths chap, that coud've been anybody's neighbour. Or uncle, for that matter...

The theorem of Pythagoras

1. is about the sides of a right-angled triangle
2. is used to calculate an unknown side
3. is invented by Pete Agoras
4. is more than 2000 years old but still going strong

The theorem of Pythagoras...

asks for the use of a very handy scheme!

Let's do exercise 8 together,

start doing 8 a), making a sketch!

Here is the sketch:

Now think hard about b:

answer for b:

Do c now:

First copy the scheme! Then:

answer for c:

Time to do d:

answer for d:

'exact' is not rounded off!

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

A few fine points from this paragraph follow now!

How to calculate length BD?!

We want to calculate BD.
What to calculate first?

Solution:   First calculate length CD in right-angled triangle ACD.

Then only calculate length BD in right-angled triangle BCD!

One more new thing from §6.2!

How (on earth) can you calculate DE or GH?

We do not even have a right-angled triangle! 

How to calculate these lengths?

Solution: we make a right-angled triangle ourself!!

With that we can make the SCHEME and calculate the unknown side.

In the next slide you see Pythagoras, going crazy about his Theorem once more...

Homework time again.

Finish as much as you can!