# Lesson Notes By Weeks and Term - Senior Secondary 1

Equal area of figures II

TERM – 2ND TERM

WEEK NINE

Class: Senior Secondary School 1

Age: 15 years

Duration: 40 minutes of 5 periods each

Date:

Subject: Technical Drawing

Topic: EQUAL AREA OF FIGURES II

SPECIFIC OBJECTIVES: At the end of the lesson, pupils should be able to

I.) Construct figures with equal area

INSTRUCTIONAL TECHNIQUES: Identification, explanation, questions and answers, demonstration, videos from source

INSTRUCTIONAL MATERIALS: Videos, loud speaker, textbook, pictures,

INSTRUCTIONAL PROCEDURES

PERIOD 1-2

 PRESENTATION TEACHER’S ACTIVITY STUDENT’S ACTIVITY STEP 1 INTRODUCTION The teacher guide the students to construct figures with equal area. Students listens attentively to the teacher and actively participate STEP 2 NOTE TAKING The teacher writes a summarized note on the board The students copy the note in their books

NOTE

EQUAL AREA OF FIGURES II

Example 1: Construct a rectangle equal in area to the triangle ABC.

Procedure

1. Draw triangle ABC.
2. Find the midpoint M of side BC and mark it.
3. Draw a perpendicular line from point A to side BC, intersecting at point D.
4. Measure the length of AD.
5. From point A, draw a line parallel to BC, intersecting AB or AC at point E.
6. Measure the length of AE.
7. Using the lengths of AD and AE, construct a rectangle with sides equal to AD and AE. Now, the constructed rectangle is equal in area to triangle ABC.

Example 2: Construct a triangle equal in area to a given regular polygon

Procedure

1. Construct the polygon ABCDEF using the given data
2. Draw the diagonals of the polygon to intersect at point O.
3. Extend the base line AB, in both directions to certain points marked M and N respectively. M and N represents the sum of the length of the side of the polygon .
4. Join OM and ON to obtain the desired triangle MON

Example 3: Construct a triangle equal in area to a given polygon with an interior angle greater than 180⁰

Procedure

1. Construct a polygon ABCDEF using a given data.
2. Extend the base line AB
3. Join DA and DB
4. Sincr angle E is opposite to line DA, draw a line from point E to line DA to meet the line AB at F
5. And again draw another line from C parallel to DB and this meets at AB produced at point G
1. Join DF and DG
2. Hence FGD is the required triangle.

EVALUATION: 1. An irregular pentagon PQRST has the following properties: PQ = TS = 60; QR = 50; PT = 40; angles PQR = 30O ; QPT = 100O; PTS = 120O.

Construct the full size of the pentagon.

(i)         Convert the triangle to a square of equal area.

(ii)        State the lengths of the base and height of the triangle.

(iii)         Convert the pentagon to triangle.

(iv)        State the lengths of the side of the square.

Construct the full size of the pentagon.

CLASSWORK: As in evaluation

CONCLUSION: The teacher commends the students positively