Jonathan Mifsud
October 27, 2020
1:17 pm
This Lesson Was Contributed By:
The Mathematics Department
This Lesson is For:
Lesson Duration:
160 mins.
What Should You Expect From This Lesson?
At the end of this lesson you will be able to: [1] Understand the notion of similar shapes. [2] Prove triangles similar by showing that: (a) The corresponding angles are equal; (b) the corresponding sides of each triangle are in the same ratio which is equal to the scale factor (k) of the enlargement; (c) there is one pair of equal angles and the sides containing these angles are in the same ratio. [3] Solve problems involving similarity and length of sides using the scale factor notio
How To Carry Out This Lesson At Home:
Lesson [1] Understand the notion of similar shapes.
Watch the following videos :
1. Defining Similar Triangles
https://www.youtube.com/watch?v=6IVyQy9F3kU
2. Enlargements produce similar shapes
https://www.youtube.com/watch?v=oPoIvNoTfUM (Watch Till 5:04)
3. Similar Triangles if corresponding angles are equal
https://www.youtube.com/watch?v=wlMuiKCYoWs
4. Using AAA property of similar Triangles to find missing angles
https://www.youtube.com/watch?v=tgFz9AfliCE
Suggested Practice:
Worksheet 1: 3 ways to Prove Similar Triangles
(document attached in Resource Section – includes Answers)
Lesson [2] Explaining why triangles are similar.
Watch the following videos:
3 ways to prove similar triangles and using the scale factor.
https://www.youtube.com/watch?v=N-EILBiYMqY
https://www.youtube.com/watch?v=gcOzJiacc0M
https://www.youtube.com/watch?v=qjoXvRAogF8
https://www.youtube.com/watch?v=3DIqvNjChpY
Note: Videos use AA~, SSS, SAS…. Locally we use AAA, RRR, RAR (see an explanation in the worksheet)
Suggested Practice:
Worksheet 2: Writing Proofs
(document attached in Resource Section– includes Answers)
Lesson [3] Finding missing sides and angles
Watch the following videos:
Using Ratio of sides to find missing sides
https://www.youtube.com/watch?v=hZpDqDypj-Q
https://www.youtube.com/watch?v=HuQh326Thkc&t=346s (watch till 5:22)
https://www.youtube.com/watch?v=TgEhYfkLMDw
Suggested Practice:
Yr 11 Tr 2 Week 3 – Similar Triangles Worksheets – Worksheet 3: Using Ratio of sides
(document attached in Resource Section – includes Answers)
