Table of ContentsTable of ContentsObjective

Review

Definition of a Triangle

Samples of Triangular Objects

Types of angles

Congruence of Line Segments

According to Angle Measure

According to Length of sides

Review Questions

Objective:Objective:

At the end of the lesson, At the end of the lesson, the students should be the students should be able to classify triangles.able to classify triangles.

TriangleTriangleIt is a It is a three three sided sided polygon.polygon.

AA

BB CC

ACAB

BC

Samples of Triangles that can be seen around us.

Acute AngleAcute Angle-It is an angle whose measure -It is an angle whose measure

is less than 90is less than 9000..

300

AA

BB

CC

<BAC which <BAC which is an acute is an acute angle.angle.

Right Angle-It is an angle whose -It is an angle whose

measure is equal to 90measure is equal to 9000..

900

Obtuse Angle- It is an angle whose - It is an angle whose

measure is greater than measure is greater than 909000 but less than 180 but less than 18000..

1500

How can we say that two segments are Congruent ?

*Two segments are congruent if and only if they have

equal length.C D

10 cm

10 cm

measure of AB = measure of CD

A B

CLASSIFICATION OF TRIANGLES

According to anglesAccording to angles

According to sidesAccording to sides

600 48O

*ACUTE TRIANGLE*ACUTE TRIANGLE-All the angles of the -All the angles of the

triangle are acute.triangle are acute.

J LJ L

KK

720 <J,<K,<L are all acute angles.

RIGHT TRIANGLERIGHT TRIANGLE-An angle in a triangle -An angle in a triangle

is a right angle.is a right angle.

909000

M OM O

NN

<M is a right angle.

leg

leg

The side opposite the right angle of a right triangle is called the hypotenuse. The other sides are called legs.

HYPOTENUSE

OBTUSE TRIANGLEOBTUSE TRIANGLE- An angle in a triangle is an obtuse - An angle in a triangle is an obtuse

angle.angle.

PP

QQ

1281280 0

<P is an <P is an obtuse angle.obtuse angle.

RR

SCALENE TRIANGLESCALENE TRIANGLE

--No two sides are congruent.No two sides are congruent.

AA

BB

AAB B == BCBC == CACA

4 cm

6 cm

CC9 cm

~~~~

D FD F

ISOSCELES TRIANGLEISOSCELES TRIANGLE--two sides of the are congruent.two sides of the are congruent.

EE

DE = FEDE = FE

basebase

legleg legleg

The two equal sides of an isosceles triangle are called legs. The third side is called the base.

~~

EQUILATERAL EQUILATERAL TRIANGLETRIANGLE

--Three sides are congruent.Three sides are congruent.

G IG I

HH

GH = HI = GIGH = HI = GI~~ ~~

Reported to:

Salvador

Salazar

Reported by: Jeremy

Javier Mr.

THETHE END!!!END!!!