PROBLEM 1A

PROBLEM 2A

PROBLEM 3A

PROBLEM 4A

PROBLEM 1B

PROBLEM 4B

PROBLEM 2B

PROBLEM 3B

TRIANGLES AS POLYGONS: CLASSIFICATION

PRESENTATION CREATED BY SIMON PEREZ RHS. All rights reserved

Standards 4 and 5

REFLEXIVE, SYMMETRIC AND TRANSITIVE PROPERTIES

EXTERIOR ANGLE THEOREM

CPCTC

ANGLE SUM THEOREM

PROBLEM 5A PROBLEM 5B

STANDARD 4:Students prove basic theorems involving congruence and similarity.

ESTÁNDAR 4: Los estudiantes prueban teoremas que involucran congruencia y semejanza.

STANDARD 5:Students prove that triangles are congruent or similar, and they are able to use the concept of corresponding parts of congruent triangles.

ESTÁNDAR 5: Los estudiantes prueban que son triángulos congruentes o semejantes y son capaces de usar el concepto de partes correspondientes de triángulos congruentes.

These are examples of POLYGONS:

These are NOT POLYGONS:

A POLYGON is a closed figure in a plane which is made up of line segments, called sides, that intersect only at their endpoints, named vertices.

Standards 4 and 5

A TRIANGLE is a three-sided polygon

Standards 4 and 5

55°

64° 61°

21°

110° 49°

RIGHT TRIANGLE

ACUTE TRIANGLE

OBTUSE TRIANGLE

CLASSIFYING TRIANGLES BY ANGLESANGLES

STANDARDS 4 and 5

PRESENTATION CREATED BY SIMON PEREZ RHS. All rights reserved

Parts of a RIGHT TRIANGLE

Leg

Leg

HYPOTENUSE

Right Angle

A

Am =180°

B

Bm+

C

Cm+If and A = 90°m then

=180°Bm+ Cm+90°- 90° -90°

=90°Bm Cm+

Conclusion: In a right triangle, both non- right angles are acute and complementary!

What kind of angles are the non-right angles in a right triangle?

CLASSIFYING TRIANGLES BY SIDESSIDES

10

4

9 22 22

9

13 13

13

SCALENE TRIANGLE

ISOSCELES TRIANGLE

EQUILATERAL TRIANGLE

Standards 4 and 5

Sample Questions

Identify the triangles by their angles and their sides

A

CB D

Right Triangles

Obtuse Triangles

Isosceles Triangles

Name the type of triangles with the following characteristics

5x 6x-5

3x+10

Find the value of x to make the triangle equilateral.

XYZ has coordinates X(2,6) Y(4,-5) Z(-3,0). Classify the triangle by angles and sides.