1. INTRODUCTION TO TRIANGLES
Class Copy: DO NOT WRITE ON OR KEEP!
GEOMETRY
INTRODUCTION TO TRIANGLES

2. Scalene Triangle: A triangle in which all the three sides are unequal in length is called a scalene triangle.

3. Isosceles Triangle: A triangle in which two of its sides are equal is called isosceles triangle.

4. Equilateral Triangle: A triangle in which have all its three sides equal in length is called an equilateral triangle.

5. Acute Triangle: A triangle which has all the three angles acute that is, less than 90°, is called an acute triangle.

6. Obtuse Triangle: A triangle whose one angle is obtuse or more than 90° but less than 180° is called an obtuse triangle.

7. Right Triangle: A triangle whose one angles is a right angle (that is 90°) is called a right triangle.

8. Triangle Sum Theorem:
The sum of the measures of three angles of a triangle is equal to 180°.
Note: If two angles of a triangle are given, we can easily find out its third angle.
A + B + C = 180°
<P + <Q + <R = 180°
50° + 60° + 70° = 180°

9. Parallelogram
A parallelogram is a flat shape with opposite sides that are parallel and equal in length.

10. Regular Polygon
A regular polygon is a two-dimensional shape with straight sides. A regular polygon has all sides equal and angles equal.

11. Irregular Polygon
An irregular polygon is a two-dimensional shape with straight sides. An irregular polygon does not have equal sides of it does not have equal angles.

12. Classify the triangle into acute triangle, obtuse triangle and right triangle with the following angles:
(a) 90°, 45°, 45° (d) 130°, 40°, 10°
(b) 60°, 60°, 60° (e) 90°, 35°, 55°
(c) 80°, 60°, 40° (f) 92°, 38°, 50°

13. COPY EACH EXAMPLE AND CLASSIGY THE TRIANGLES BY ITS SIDES
COPY EACH EXAMPLE AND CLASSIGY THE TRIANGLES BY ITS SIDES.EQUILATERAL equilateral, isosceles and scalene triangles.
(a) 6 cm, 3 cm, 5cm. (d) 8 cm, 12 cm, 10 cm
(b) 6 cm, 6 cm, 6 cm. (e) 3 cm, 4 cm, 5 cm.
(c) 7 cm, 7 cm, 5 cm. (f) 3.5 cm, 3.5 cm, 4.5 cm.

14. Assignments: Choose One!
Go to this website: interactive.html
Create 5 different triangles with their measures and points, then copy them onto paper (with their angles and points). This must be done for all 6 types of triangles.
On a sheet of paper, draw 2 triangles for each type of triangle (all 6). Use a protractor and pencil to help you out with angles. Make sure you include the degrees inside of the triangle and points.
See Ms. Payne or Mr. Rollins for worksheet: Find the Missing Angle in all of the triangles and label them according to what type of triangle they are.