5.5 A projection, cross sections and Pythagoras in 3D

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

Today

- I am able to draw a cross section parallel to a given plane through a given point.

- I am able to use Pythagoras’ theorem to calculate space diagonals.

Parallelprojection 

In a parallelprojection, lines which are parallel in the original figure are drawn parallel.

You've learned to use this projection last year.

Parallelprojection 

Consider these three
parallel cross sections in this cuboid.

Cross sections create parallel line
segments on parallel faces of the 
original 3D figure.

So AK // BL and MN // CD.

Parallelprojection 

Consider these three
parallel cross sections in this cuboid.

The edges of parallel cross sections
are parallel in parallel planes.

So AK // DN and KL // MN.

Finish exercise 45 on the worksheet. Photograph your work.

Calculate AG.

Practice!