1819 C2X §8.Refresh & §8.1

• Wiskunde
• Middelbare school
• havo, vwo
• Leerjaar 2

What number should be written on the dots?
1.25 km = .... m

What number should be written on the dots?

50cm​2​​=...mm​2​​

Converting units of length and area

Units of length are multiplied/divided with steps of 10

Units of area are multiplied/divided with steps of 100

Enclosing figures (R3g)

Calculate the area of figures ABCD, KLM and PQR by enclosing.

When enclosing a figure, you use the fact that the area of a right-angled triangle is half a rectangle.

Enclosing figures (R3g)

Calculate the area of figures ABCD, KLM and PQR by enclosing

Area ABCD:

Area red square = 

Area triangles on outside =

Area ABCD = 

4⋅4=16

​2​​3⋅1​​=1.5

16−4⋅1.5=10

Pythagoras' theorem

If you know two sides of a right angled triangle, you can calculate the third side using Pythagoras' Theorem:

Pythagoras' theorem

Calculate the lenght of side AC in triangle ABC, where BC = 13, AB = 5 and angle A is 90°

Pythagoras' theorem

Calculate the lenght of side AC in triangle ABC, where BC = 13, AB = 5 and angle A is 90°

Pythagoras' theorem

Calculate the lenght of side AC in triangle ABC, where BC = 13, AB = 5 and angle A is 90°

Pythagoras' theorem

Calculate the lenght of side AC in triangle ABC, where BC = 13, AB = 5 and angle A is 90°

Area of triangles

Make exercise 1  from §8.1

Area of triangles

Area of triangles

Base and height of a triangle

The base is one side of a triangle.

The height  is the distance from the base to the opposite vertex.

The height is perpendicular to the base.

In a triangle there are 3 base/height combinations.

Base and height of a triangle

The height of a triangle can also be outside the triangle, perpendicular to the line through the base.

Area of a triangle

The area of a triangle can be calculated with the formula:

This can be shortened to:

                                          or 

Area of a triangle

HW Tuesday 11-6

Make and correct §8.Refresh and §8.1