Lesson Notes By Weeks and Term - Senior Secondary 1

Inscribed and circumscribed circle

TERM – 2ND TERM

WEEK ONE

Class: Senior Secondary School 1

Age: 15 years

Duration: 40 minutes of 5 periods each

Date:

Subject: Technical Drawing

Topic: INSCRIBED AND CIRCUMSCRIBED CIRCLE

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

I.) Inscribing a circle to a given triangle

II.) Circumscribing a circle to a given triangle

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 explains the meaning of inscribing and circumscribing to the students Students listens attentively to the teacher STEP 2 EXPLANATION Teacher guide students to inscribed and also circumscribe a circle to a given triangle respectively. Students exhibit attentiveness and active engagement STEP 3 NOTE TAKING The teacher writes a summarized note on the board The students copy the note in their books

NOTE

INSCRIBED AND CIRCUMSCRIBED CIRCLE

Inscribing a circle to a given triangle

A circle can be inscribed inside a triangle if the center of the circle lies at the intersection of the triangle's angle bisectors, and the radius of the circle is the distance from the center to any of the triangle's vertices. An Inscribed circle is a circle that is drawn inside a triangle touching all three sides.

To draw an inscribed circle, we need to bisect TWO inside angles,

drop a perpendicular and draw the circle inside the triangle.

Circumscribing a circle to a given triangle

A circle can be circumscribed around a triangle if the center of the circle lies at the intersection of the perpendicular bisectors of the triangle's sides, and the radius of the circle is the distance from the center to any of the triangle's vertices.A Circumscribed circle is a circle that is drawn outside of a triangle and touches all three vertices.

To draw a circumscribed circle, we need to bisect TWO sides and draw the circle outside the triangle touching vertices A, B and C.

EVALUATION: 1. Given a triangle, what's the difference between the inscribed circle of the triangle and the circumscribed circle of the triangle?

1. Construct a triangle PQR with side PQ = 80, and angle PQR =

QPR = 60° (Show all construction lines).

(i)        Find the lengths PR and QR.

(ii)       Inscribe a circle in the triangle PQR.

(iii)      Name the triangle PQR.

CLASSWORK: As in evaluation

CONCLUSION: The teacher commends the students positively