# 3Tvwo §6.3 / 3Thavo §6.4

§6.3 Sine and cosine
First a look back at §6.2!
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Slide 1: Slide
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This lesson contains 18 slides, with interactive quizzes and text slides.

Lesson duration is: 50 min

## Items in this lesson

§6.3 Sine and cosine
First a look back at §6.2!

2a
If 6 =

then a = ......

a32
If 4 =

then a = .....

#### Slide 3 -Mind map

Using the tangent to calculate the angle of elevation.
+ Take an empty space in your notebook and first
+ Make a Sketch of this:

The Sketch:

#### Slide 5 -Slide

Now calculate:

+ the angle of elevation
+ using         a. your Sketch  and

Solution:

#### Slide 7 -Slide

Difference between a tangent and an angle.
A
there is none, in fact
B
a tangent is about steepness; an angle is not
C
an angle is in degrees; a tangent is a number
D
an angle is a number; a tangent is in degrees

#### Slide 8 -Quiz

you use 'shift tan' on the Casio, when you
A
know the angle and you want to know the tangent.
B
know 2 sides of a right-angled triangle and you want to calculate the 3rd side.
C
know the tangent and you want to know the angle.
D
want to round an angle to a whole number of degrees.

#### Slide 9 -Quiz

Homework time.
Do §6.3 now.
Later this LessonUp will be continued.
timer
5:00

#### Slide 10 -Slide

What's new in §6.3 ?
A lot!
The reason for this: sometimes it is better to use:
SINE or COSINE than TANGENT!
Just watch the next slide!
You will also see a way to remember all three of them!

#### Slide 12 -Slide

Three more things...
1.       Which angle is meant?
2.      A mistake in the book!
3.       A joke (or two).

#### Slide 14 -Slide

1.   Which angle do you mean?!?

#### Slide 15 -Slide

2.  Mistake in the book, p.201:
16d, 'Angle S' should be 'Angle P'!
Correct this, with a pencil.

#### Slide 17 -Slide

Homework time again.
Try to finish the paragraph.