Congruence and Similarity 4

Congruence and Similarity 4

Learning Goal

To apply the rules of similarity to identify similar triangles

RECAP

Two triangles are considered to be similar if one of them can be scaled up or down in size, and then rotated and/or reflected to match the other.

RECAP

Similar figures have the following properties:

• Corresponding sides are proportional

• Corresponding angles are equal.

Multiple Choice

RECAP QUESTION

Are the following pair of triangles similar?

• Yes

• No

Fill in the Blank

To make the pair of triangles similar, what number should be in place of 27?

Answer - just number

Multiple Choice

RECAP QUESTION

Are the pair of triangles similar?

• Yes

• No

ANSWER

The pair of triangles are NOT similar because the corresponding angles are not equal

RECAP

Scale factor

Multiple Choice

What is the scale factor of this pair of similar figures?

• 6

• 3/18

• 18/3

Fill in the Blank

The pair of triangles are similar. Find the value of x

Answer 'x=___' (no spaces, no units)

Similarity tests for triangles

There are four tests that we can use to test similarity between two triangles. If any one of these tests is satisfied then the two triangles must be similar.

Test for similarity

• AAA: Three pairs of equal angles

• SSS: Three pairs of sides in the same ratio

• SAS: Two pairs of sides in the same ratio and an equal included angle

• RHS: Both have right angles, and the hypotenuses and another pair of sides are in the same ratio

Question 1 (discussion)

Are △ABC and △DEF similar?

You will input your answers in the next slide

Multiple Choice

Are △ABC and △DEF similar?

• Yes

• No

Multiple Choice

The pair of triangles are similar. Which test is satisfied?

• SSS

• SAS

• ASA

• RHS

Multiple Select

Question 2

Which two of the following triangles are similar?

Multiple Choice

The pair of triangles are similar. Which test is satisfied?

• SSS

• SAS

• ASA

• RHS

QUESTIONS TO COMPLETE

Exercise 7G: Questions 1-10