1. TRIANGLES
Based on sides.

2. TRUE OR FALSE Every triangle has three sides. ( )
In an equilateral triangle, all three internal angles are also congruent to each other and are each 65°. ( )
In an isosceles triangle, the angles opposite the equal sides are also equal. ( )
A scalene triangle is a triangle that has three equal sides. ( )
An isosceles triangle can be equilateral. ( )
All equilateral triangles are acute. ( )
Every equilateral triangle is also isosceles. ( )

3. EQUILATERAL TRIANGLE
Aim: To construct an equilateral triangle given the length of one side.

4. EQUILATERAL TRIANGLE

5. EQUILATERAL TRIANGLE

6. ISOSCELES TRIANGLE
Aim: To construct an isosceles triangle given the length of the base and one side.

7. ISOSCELES TRIANGLE
Draw a line segment of the given length of the base.
2. Set the width of your compass equal to the length of one of the equal sides.
3. Place the spike of the compass on one of the end points of the base (drawn in the first step), and draw an arc on either side of the base.
4. Without changing the width, place the spike of the compass on the other end point of the base. Draw another arc so as to cut the arc drawn in the previous step at some point.
5. Connect the point of intersection of the two arcs to each end point of the base. The closed figure formed is the unique isosceles triangle adhering to the given dimensions.

8. SCALENE TRIANGLE
Aim: To construct an scalene triangle given the length of three sides.

9. SCALENE TRIANGLE

10. SCALENE TRIANGLE

11. SCALENE TRIANGLE

12. PRACTICE
Construct the triangle with the given side length proportions.
1. Equilateral: 3-3-3
2. Isosceles:
3. Scalene: 3-4-5

13. Height of a triangle What is a base? Base means bottom.
What is height?
The height of any object is how much it measures from its top to its bottom.
How do you identify the base of a triangle?
Any of the three sides of a triangle can be considered the base of the triangle.
How do you identify the height of a triangle?
The height of a triangle is the perpendicular line dropped onto its base from the corner opposite the base.

14. Height of a triangle
The height of a triangle corresponds to its base. If the base changes, so does the height.
The height of a triangle is the shortest line onto the base from its opposite corner.
The height of a triangle may be outside the triangle.

15. ACUTE TRIANGLE

16. OBTUSE TRIANGLE

17. RIGHT TRIANGLE