Area of a rectangle and triangle

• Wiskunde
• Middelbare school
• havo, vwo
• Leerjaar 1

Welcome to maths

Need: 

• Book open on p. 119
• Notebook open on an empty page (with a margin)
• Pen 
• Pencil (+sharpener and eraser)
• Geo triangle

 Did you check your homework?

Yes? Start with ex. 25 and 27 on p. 115

No? first check and correct your homework

perimeter = omtrek 

area = oppervlakte

shape = figuur

to express = uitdrukken

Goal

• Repeat §1 and §2
• Know what an area is and how to calculate an area 
• Write down calculations in a short and formal way
• Check your work 

Make your own short question about §1 and/or §2.
For instance:
'Calculate the area of a rectangle of 20 cm by 30 dm in m^2.'
Or 'Convert 10.3 hours to minutes.'

Calculate the area of this triangle and share your workings.

- Area of a triangle =
- What is the base?
- Whats is the height?

​2​​1​​⋅base⋅height

Calculate the area of triangle DEF and share your workings.

- Area of a triangle =
- What is the base?
- Whats is the height?

​2​​1​​⋅base⋅height

Convert.
a. 75 cm^2 = ..... mm^2
b. 120 000 cm^2 = ...... m^2
Extra:
c. 810 mm^2 = ..........dm^2

Answer like this : 

75 / 12 / 81

Next slide

•  Make an right angled triangle
• Make an acute triangle
• Make an obtuse triangle

Per triangle: find the right height and show your neighbor or teacher

www.geogebra.org

Work on...

• exercises 34 utai 36 on p. 123
• Check your work after 8 minutes with a different colour
• Copy HW in your planner
• HW: Do ex. 25, 27 and 34 utai 36  on p. 119 and p. 123

Next lesson

• You have finished and checked your homework 
• HW: Do ex. 25, 27 and 34 utai 36 on p. 119 and p. 123
• We will work on area and 'The box method'