Download LESSON PLAN School Unit : Junior High School Subject

LESSON PLAN
School Unit
: Junior High School
Subject
: Mathematics
Year
: VIII
Semester
:1
A. Standard of Competency
: Use Pythagorean Theorem in problem solving
B. Basic of competency
:
Use Pythagorean Theorem to determine the length of
right triangle side
C. Indicators
:
1. Find Pythagorean Theorem
2. Compute the length of a right triangle side if two other sides are known
3. Compute proportion of special right triangle sides (the measure of one angle is 30 0,
450, and 600 )
4. Determine three number are Pythagorean triple
D. Time allocation
: 8 x 40 minutes (four meeting)
E. Learning Achievement
After studying this lesson, students will be able to
a. Determine the formula of Pythagorean theorem by investigation
b. Use Pythagorean theorem to compute the length of a right triangle side if two other
sides are known
c. Determine the proportion of special right triangle sides (the measure of one angle is
300, 450, and 600 )
d. Find three number are Pythagorean triple
e. Use Pythagorean triple to proof a triangle is a right triangle
F. Topics
Pythagorean Theorem
1. Proportion of special right triangle
For any right triangle, the square of the length of the hypotenuse force equal to the
square of the length of the side of the elbow.
1
If ABC is a right triangle with 𝑎 hypotenuse length, while 𝑏 and 𝑐 are the length of
the elbows then apply.
𝑎2 = 𝑏 2 + 𝑐 2
The above statement if it is converted into a subtraction form.
𝑏 2 = 𝑎2 − 𝑐 2
or
𝑐 2 = 𝑎2 − 𝑏 2
2. Pythagorean triple
Pythagorean triple is a group of three positive integers that satisfy the greatest number
equal to the square of the number of squares of the other two numbers.
G. Method, approach, and model
Learning method : Cooperative, Inductive, and guides discovered
Method
: Discussion
H. Learning activities
First meeting

Preface
a. Reminds about the area of square, triangle, square, and square root
b. Mention one example of applying of Pythagorean theorem in daily life

Main Activities
c. Makes group of four
d. Gives problem about right triangle to discussed in group
e. Students discuss about relation between the area of square with side
hypotenuse and square with side right triangle sides. The length of sides are
different between one group and other group
f. Each group asked to present their result
g. Teacher and students together conclude their discussion
h.
Based their conclusion, teacher explain the formula of Pythagorean theorem
2
i. Students write the formula of Pythagorean theorem

Closing
j. By teacher’s guide, Students conclude their lesson
k. Reflection
l. Gives homework
Second Meeting

Preface
a. Discuss difficult homework
b. Reminds students about formula of Pythagorean theorem
c. Informs learning achievement
d. Informs that today we will apply Pythagorean theorem in daily problem

Main activities
e. In group, students discuss about how to use the formula of Pythagorean
theorem on right triangle
f. Explain how to compute the length of a right triangle side if two other sides
are known
g. Students do exercise

Closing
h. By teacher’s guide, Students conclude their lesson
i. Reflection
j. Gives homework
Third Meeting

Preface
a. Remind students about the formula of Pythagorean theorem and the
properties of equilateral triangle
b. Informs to students that if they understand this topics, they can solve daily
problem that related with Pythagorean theorem

Main activities
c. Gives equilateral triangle that its sides are known, then make altitude from
one angle so that made right triangle that one its angle is 300 or 600
d. From the right triangle that made, students asks to calculate the length of
altitude of equilateral triangle
3
e. Based on its right triangle sides, students asks to find the proportion of
special right triangle sides
f. Gives exercise with the measure of one angle is 450

Closing
g. By teacher’s guide, Students conclude their lesson
h. Reflection
i. Gives homework
Fourth Meeting

Preface
a. Remind students about the formula of Pythagorean theorem
b. Informs to students that by Pythagorean theorem they can know the kind of
triangle

Main activities
c. Prepare some group of numbers, each group contain of three numbers.
Students asked to determine the group of numbers are Pythagorean triple by
checking use Pythagorean theorem
d. Gives the measure of triangle sides, then asked students to check whether is
right triangle or obtuse triangle or acute triangle
e. Students do exercise

Closing
f. By teacher’s guide, Students conclude their lesson
g. Reflection
h. Gives homework
I. Tool and References
Text book, white board, ruler, and triangle model
4
J. Assessment
Kind
: formative test, discussion result
Form
: Essay, presentation
Example:
1. Observe the following right triangle!
A
b
C
c
a
B
Determine relation between a, b, and c!
2. A right triangle has hypotenuse of 17 cm and the length of one right triangle side is 15
cm. Determine the length of other right side, then compute it’s area!
3. Express proportion of following right triangle sides!
C
3 cm
B
300
A
4. Which of the following number group are Pythagorean triple
a. 12, 13, 15
b. 6, 8, 9
c. 20, 21, 29
d. 14, 16, 20
5. know triangle ABC having sides AB = 24 cm, AC = 7 cm, BC = 25 cm. Proof that
triangle ABC is right triangle!
5