Lp Final Trigo.docx

Lesson Plan TRIGONOMETRIC FUNCTIONS (SOH-CAH-TOA) Grade 9 Mathematics - Section Molave Monday (8:40am-9:40am) I Objectives: At the end of the lesson, the Learners will be able to: 1. use appropriately the correct ratio to use in the given problem. 2. use scientific calculator in solving trigonometric ratios 3. use trigonometric ratios to solve for an unknown length of a side of a right triangle, given an angle and a length of a side. 4. use trigonometric ratios to solve for an unknown angle of a right triangle, given the length of two sides. 5. appreciate the concept of trigonometric ratios in real life situation II Subject Matter: Content Standards: Demonstrates understanding of the basic concepts of trigonometry. Learning Competency: Illustrates the six trigonometric ratios: sine, cosine, tangent, secant, cosecant, and cotangent. Topic: TRIGONOMETRIC FUNCTIONS (SOH-CAH-TOA) Textbook: Mathematics Learner’s Material Materials: Audio visual presentation, Chalk board, Textbooks. III Learning Procedure: A. Preliminary Activities: 1. Prayer 2. Greetings 3. Checking of Attendance B. Motivation and Review: The class will recall what thus SOH-CAH-TOA means; this will be done as a group of 5.

C. Lesson Proper: Activity I: Finding an angle from a triangle “Jigsaw Puzzle Approach” This strategy involves students becoming “experts” on one aspect of a topic, then sharing their expertise with others. Divide a topic into a few constitutive parts (“puzzle pieces”) the topics will be finding an angle from a triangle using COSINE, TANGENT and SINE.  

There will 6 subgroups that will be formed 2 subgroups per topic and each subgroup will be assign with different “piece” of the topic. Each group’s task is to develop expertise on its particular subtopic by brainstorming, developing ideas, and if time permits, researching. Once students have become experts on a particular subtopic, shuffle the groups so that the members of each new group have a different area of expertise.

To find a missing angle from a right-angled triangle we need to know two of the sides of the triangle. We can then choose the appropriate ratio, sin, cos or tan and use the calculator to identify the angle from the decimal value of the ratio.

Subgroups 1&2 Using Cosine

adjacent hypotenuse

a h

6 14

Subgroups 3&4 Using Tangent opposite adjacent

o a

8 3

Subgroups 5&6 Using Sine opposite hypotenuse

o h

10 12

Analysis: Activity 2: Finding a side from a triangle “Using Discovery Approach” This activity will be a paired activity they need to discover something some the idea given by the teacher. To find a missing side from a right-angled triangle we need to know one angle and one other side. 1. What have you observe on the idea given? 2. How did it differ from the former example? 3. What do you think will the next step in solving this kind of problem?

Activity 3: Finding a side from a triangle “Board work Approach”

Using Cosine

Using Tangent

adjacent hypotenuse

o a

a h

Using Sine

o h

Abstraction: SOH-CAH-TOA Trigonometry is concerned with the connection between the sides and angles in any right angled triangle.

The sides of a right -angled triangle are given special names:  The hypotenuse, the opposite and the adjacent.  The hypotenuse is the longest side and is always opposite the right angle.  The opposite and adjacent sides refer to another angle, other than the 90o.

Integration of Technology in the learning process Using trigonometry on the calculator All individual angles have different sine, cosine and tangent ratios (or decimal values). Scientific calculators store information about every angle. We need to be able to access this information in the correct manner. Using ratios to find angles We have just found that a scientific calculator holds the ratio information for sine (sin), cosine (cos) and tangent (tan) for all angles. It can also be used in reverse, finding an angle from a ratio. To do this we use the sin-1, cos-1 and tan1 function keys.

Application: Solve for the unknown values 1.

2.

3.

Assessment: Your turn, find the value of “r”, use any trigonometric ratio if applicable.