# 1TH/Vwo §4.4 Measuring angles

§4.4 Measuring angles ...

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Slide 1: Slide
WiskundeMiddelbare schoolhavo, vwoLeerjaar 1

This lesson contains 32 slides, with interactive quizzes, text slides and 1 video.

Lesson duration is: 50 min

## Items in this lesson

§4.4 Measuring angles ...

#### Slide 1 -Slide

1TH/Vwo §4.4 Measuring angles

First a quick check on your knowledge of §5.3 !
Try to give the good answers, gaining points.

#### Slide 2 -Slide

an angle of 90 degrees is a(n) ...
A
straight angle
B
obtuse angle
C
right angle
D
acute angle

#### Slide 3 -Quiz

An angle of 47 degrees is a(n)
...... angle.
A
obtuse
B
right
C
acute
D
straight

#### Slide 4 -Quiz

An obtuse angle could be ...
A
99 degrees
B
36 degrees
C
90 degrees
D
180 degrees

#### Slide 5 -Quiz

an angle of 103 degrees is a(n)
angle
A
acute
B
right
C
obtuse
D
straight

#### Slide 6 -Quiz

I wonder if    .....
+ you had both wrong, having no clue
However, let's look back at the Theory from §4.3 !

#### Slide 10 -Slide

Attention (1):
+ a right angle has :
+ an acute angle has a number of degrees between  0  and  90.
90°

#### Slide 13 -Slide

Attenzione (2):
+ an obtuse angles has a number of degrees between 90 and 180
+ a straight angle has 180 degrees

#### Slide 16 -Slide

Soon comes a Movie.

#### Slide 17 -Slide

Measuring angles ...
+ you can do with the GEO TRIANGLE:
using the PROTRACTOR ( =gradenboog) on it
+ that's the semi-circle (=half a circle) with the degrees from 0 - 180 degrees
written on it
+ just watch the following Movie and be amazed!

#### Slide 18 -Slide

Ruben ...
surely knows how to explain things in a simple way!
By the way, I offer you this Dutch movie, because it was the only one I found that used a Geo triangle and not a compass rose!

#### Slide 20 -Video

Now...
Your teacher will demonstrate how to MEASURE angles
with a GEO triangle.
After this Ruben will take over!
(But who the heck is Ruben?!)

#### Slide 22 -Slide

How many degrees is angle P?
First notice this:
+ the 0-point of the GEO lies on the vertex of the angle
+ the longest side of the GEO lies along one of the arms of the angle

#### Slide 23 -Slide

How many degrees is angle P?
We read off 64 degrees and also 116 degrees.
Is this angle acute or obtuse? It's acute because it lies between
0 and 90 degrees.
So 64 degrees is the good answer!

#### Slide 25 -Slide

Homework time
Correct them with the Solutionsbook.
Later a few more slides follow.
Good luck!

timer
15:00

#### Slide 26 -Slide

3 special things:

+ A difficult word for your wordlist
+  Which angle is meant?
+ How to measure an angle if the arms are too short?
Just watch the next slides!

#### Slide 27 -Slide

an AUXILIARY line - een hulplijn
in opposite directions - in tegengestelde richtingen
a pentagon - een vijfhoek
a hexagon - een zeshoek

#### Slide 28 -Slide

If the arms of an angle are too short, just ....
extend them!
So in this case
make both arms longer,
so that the geo can be used well!
(You may even do this in your Textbook,
but with a PENCIL, of course!)

#### Slide 30 -Slide

In the picture you see many different angles:
+ angles A, C and E , but also
+ angles B1, B2, D1 and D2 !
+ so by the added number you
know which part of the angle
is meant. Great!

#### Slide 31 -Slide

Time for Homework
+ Do:    § 4.4 Measuring angles
+ Check your work with the Solutionsbook
+ take pics and
+ send in all the stuff on Google Classroom