1819 C2X §4.3

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

Which exercises/theories should I discuss on the board?

Similar figures

If two figures are enlargements of each other, we say they are similar figures.

In similar figures you have pairs of corresponding angles and pairs of corresponding sides.

Similar figures

Are two figures similar?

To find out if two figures are similar, you have to check:

- are all corresponding angles equal?

- are all corresponding sides multiplied with the same scale factor?

If both are true, then the figures are similar.

Are two figures similar? NOTATION!

1) Check if the corresponding angles are equal:

- Calculate missing angles if needed

- List all pairs of corresponding angles

- If all pairs are equal, move on to step 2. If all pairs are not equal the figures are NOT similar.

Are two figures similar? NOTATION!

2) Check if the corresponding sides are multiplied with the same scale factor.

- List all pairs of corresponding sides (in a table)

- Calculate the scale factor for each pair

- If the scale factor is equal for each pair, the figures are similar. If the scale factor is NOT equal for each pair, the figures are NOT similar.

Are two figures similar? NOTATION!

1) Check if the corresponding angles are equal:

The angles are not equal

therefore ABC and KLM are

NOT similar.

(Step 2 is no longer needed)

Are two figures similar? NOTATION

So all corresponding

angles are equal.

Are two figures similar? NOTATION

All sides are NOT

multiplied with the

same factor.

ABCD and EFGH are

NOT similar.

HW Monday

• Make exercises §4.3:

Support: 17, 18, 19, S20, S21, 22, 23

Standard: 17, 18, 19, 20, 21, 22, 23

Challenge: 17, 18, 19, 20, 21, 22, C4

• Correct with a red pen