# 2Tvwo §6.2 Calculating a side

§6.2 Calculating a side
Do you remember our old, bearded friend from the past?
1 / 36
Slide 1: Slide
WiskundeMiddelbare schoolvwoLeerjaar 2

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

Lesson duration is: 50 min

## Items in this lesson

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

Who is he?

#### Slide 3 -Mind map

Solution:
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
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 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!

timer
0:45

#### Slide 12 -Open question

Here is the sketch:
Of course this triangle could
As long as angle K is 90 degrees!

timer
0:45

#### Slide 15 -Slide

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

#### Slide 18 -Slide

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

#### Slide 20 -Slide

Time to do d:

Think about the meaning of the words: 'exact length'.

#### Slide 21 -Slide

'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.
USE THE METHOD SHOWN ABOVE EXERCISE.
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,
+  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 25 -Slide

A few fine points from this paragraph follow now!

#### Slide 26 -Slide

We want to calculate length BD.
What to calculate FIRST?

#### 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 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!