Department of Education
Region III
Division of Pampanga
PAGUIRUAN HIGH SCHOOL
Paguiruan, Floridablanca, Pampanga
SEMI-DETAILED LESSON PLAN IN MATHEMATICS 9
I.
Standards and Objectives
Standards
Content Standard: The learner demonstrates understanding of the basic concepts of
trigonometry.
Performance Standard: The learner is able to apply the concepts of trigonometric
ratios to formulate and solve real-life problems with precision and accuracy.
Competency: Competency44: the learner finds the trigonometric ratios of special
angles. (M9GE -IVb-c-1)
Objectives
At the end of the lesson the students should be able to:
a. determine trigonometric ratios involving special angles.
b. compute the numerical values of trigonometric expressions involving special angles.
c. show accuracy in identifying special angles and formulation of new and easy ways of
solving trigonometric expressions involving special angles.
II.
Subject Matter
Topic:
Trigonometric Ratios of Special Angles
Resources:
Mathematics 9 – Learner’s Material, p.448-450
III.
Materials
E-Whiteboard
PowerPoint Presentation
Laptop
Square and Triangle cutouts,
Protractor, Ruler, Scientific calculator
IV.
Procedure
A. Preparation
a. Opening Prayer
b. Checking of attendance
c. Classroom management
B. Review of Previous Lesson (Solving Triangles using Trigonometric Functions) (10 mins.)
Review the previous evaluation given to the students to refresh their minds of the past lesson
which is connected to the lesson to be presented.
2.)
1.)
C. Motivating Activity – (Special Angles presented using cutouts) (10 mins.)
1) Given cutouts of a square and an equilateral triangle, form a diagonal on both of the
given figures and fold them in half and form two triangles on each of the figures.
2) Measure all the angles inside each of the newly formed triangles.
3) Notice the similarities and relationships between the legs of the triangle formed from
the square.
4) Notice the relationship between the hypotenuse and shortest side of the triangle
formed from the equilateral triangle.
Department of Education
Region III
Division of Pampanga
PAGUIRUAN HIGH SCHOOL
Paguiruan, Floridablanca, Pampanga
D. Lesson Proper (10 mins.)
The teacher will discuss the key concepts on special angles 30 – 45 – 60.
E. Application (10 mins.)
Let the learners solve triangles using the concepts discussed, see activity 3 on page 450. Guide
them as they answer on the board. Call them one by one by drawing their names on the screen
to add more excitement to the class. Focus on targeting and addressing their difficulties and
queries during this period.
F. Generalization
In this lesson you have learned the process of determining values of expressions involving
trigonometric ratios of special angles even without the use of a calculator. Remember the two
special right triangles are the 30 – 60 – 90 triangle and the isosceles (45 – 90 – 45) triangle.
Your understanding of this lesson and other previously learned concepts will help you facilitate
your learning in the next lesson : the angle of elevation and angle of depression.
G. Evaluation (10 mins.)
Continue on solving triangles using the concepts discussed, see activity 3 on page 450 and
answer the remaining items that were not taken during discussion. Write your answers on a
separate sheet of paper.
H. Assignment
Create your own equilateral triangle and square cutouts, label all the parts of each triangles
formed proving the 2 Special Right Triangle Theorems. Make use of colored papers or
magazines. Write the measurements and computations at the back of each figure.
Prepared by:
Noted by:
RUSSELL L. RAMOS
Teacher I
ANALIZA G. PUSUNG
Principal I
Department of Education
Region III
Division of Pampanga
PAGUIRUAN HIGH SCHOOL
Paguiruan, Floridablanca, Pampanga