3Tvwo §6.4 / 3Thavo §6.5 Calculating in right-angled triangles.

• Wiskunde
• Middelbare school
• havo, vwo
• Leerjaar 3

§6.4 / §6.5 Calculating in right-angled triangles

Choose the right Formula-in-letters, that tells you how to calculate the 

SINE,   COSINE  and  TANGENT, in the next slide.

vwo §6.4 / havo §6.5

 Calculating in right-angled triangles

Because it's been a while since you worked on this Chapter -holiday!- we will look back shortly on the

content you learned up to now!

VWO classes:   STUDY SQUARERS, feel free to go to the STUDY SQUARE, doing § 6.4 on your own.

The correct letterformula is:

1. SAH COA TAH
2. SIN COS TOA
3. COH TAH SIN
4. SOH CAH TOA

Answer: SOH CAH TOA

meaning:

Sine = Opposite shorter side / Hypotenuse

Cosine = Adjacent shorter side / Hypotenuse

Tangent = Opposite shorter side / Adjacent shorter side

§6.4/§6.5 Calculating in right-angled triangles

You now know the:

+  sine, cosine and tangent

+ but when do you use which of these?

+ that is shown in the next slides!

+ FIRST WE DO 21 TOGETHER!

Homework time.

+    Do §6.4 vwo / §6.5 havo Calculating in right-angled triangles

+    Later a new technique will be explained, that you need to do         the last 3 exercises!

Explanation for the last 3 exercises of the paragraph.

If you want to calculate length PQ,

then              what is the problem? 

Key in your answer in the next slide!

What's the pro, bro (sis)?
So: describe the problem!

Answer:

The big problem is:

there is no right angle to be seen?!

Pythagoras only works in right-angled triangles!

The method to solve this problem is shown in the next slide.

Now there are even two right-angled triangles!

REMEMBER: WE ARE AFTER: length PQ!!

1. draw auxiliary line (=helplijn) RS.

2. calculate RS with sine angle P

3. calculate PS with cosine angle P (or tangent angle P)

4. calculate QS with tangent angle Q

5. add PS to QS to get length PQ

helping line = auxiliary line

Homework time again.

In the next slide an Oldie-but-Goldie...