Triangle similarity

Abstract

Triangle similarity & the trigonometric ratios is the fundamental to trigonometry. This lesson is developed with CCRS G.SRT.5 Geometry: Similarity, Right Triangles.

Learner Audience / Primary Users

Students newly get to know trigonometry.

Educational Use

• Curriculum / Instruction

• Informal Education

College & Career Readiness Standards (CCRS) Alignment

• Subject: Mathematics

• Domain or Strand:

• Domain:

trigonometry

• Standard Description:

Use congruence and similarity criteria for triangles to solve problems and to prove relationships in geometric figures.

English

Material Type

• Instructional Material

• Other OER

Learning Goals

The purpose of this lesson is for learners to be able to:

• Use congruence and similarity criteria for triangles to solve problems and to prove relationships in geometric figures.

Keywords

• Designers for Learning

• Trigonometry

30 minutes

No

A computer with Internet access

• Lesson Author: Rongsheng Wang

Instructional Strategies and Activities

Warm-Up

Time: 2 minutes

Show students with some right triangles, as well as some triangles with similarity.

Introduction

Time: 3 minutes

Introduce the definition and concepts of Triangle similarity & the trigonometric ratios.

Presentation / Modeling / Demonstration

Time: 10 minutes

PowerPoint presentation to students with key terms, and play the Khan Academy video clip to them.

Guided Practice

Time: 5 minutes

Lead the students to distinct whether two given triangles are similarity.

Evaluation

Time: 5 minutes

Give students a few sets of triangles, and ask them to distinct whether any of them are similarity.

Application

Time: 5 minutes

Lead students to brainstorm how similarities can be used in daily life, e.g. modelling,architectural design, etc.