lines, properties of parallel lines, triangles

2. The Course Content
Lines & Angles Properties Of
Parallel Lines
Properties Of
TrianglesParallel Lines Triangles

4. Lines and Angles
At first I would like to explain Lines ….!

5. Somemore typesofLines.

6. Angles
Types Of Angle Description
Acute Angle an angle that is less than
90°.
Right Angle an angle that is 90° exactly.
Obtuse Angle an angle that is greater
than 90° but less than
180°.
Straight Angle an angle that is 180°
exactly.
Reflex Angle an angle that is greater
than 180°.

8. Properties of Parallel Lines
At first, we should know,
 What is Parallel line?
:- Lines are said to be parallel when they do not intersected however if
extended.
What is Transversal? What is Transversal?
:- A line which intersect two or more lines at distinct points is called
Transversal.
.

9. Properties
 Corresponding angle
(∠1, ∠5), (∠2, ∠6), (∠3, ∠7) & (∠4,
∠8)
 Alternate Interior angle
(∠3, ∠5) & (∠4, ∠6)
∠ ∠ ∠
∠ ∠ ∠ ∠
 Alternate Exterior
angle (∠2, ∠8) & (∠1,
∠7)
 Consecutive interior
angle (∠3, ∠6) & (∠4, ∠5)
-----------------------Linear Property
Sum of all angles on a line = 180°

11. Properties of Triangles.
At first, we should know,
 What is a Triangle?
vertic
A triangle is a polygon with three edges and three
es. It is one of the basic shapes in geometry.
Triangles are divided into two basis:Triangles are divided into two basis:
 On the basis of length of Sides.
 On the basis of the angles of
sides.

12. On the basis of sides.
(i) Equilateral triangle: An equilateral triangle is a triangle that has all equal sides.
(i) Equilateral triangle (ii) Isosceles triangle (iii) Scalene
triangle
(i) Equilateral triangle: An equilateral triangle is a triangle that has all equal sides.
(ii) Isosceles triangle: An isosceles triangle is a triangle that has two
equal sides. The following is an isosceles triangle

13. (iii) Scalene triangle: A scalene triangle is a triangle that has
no equal sides. The following is a scalene triangleno equal sides. The following is a scalene triangle

14. On the basis of Angles.
(i) Acute Triangle (ii)Right triangle (iii) Obtuse Triangle
(i) Acute triangle: In an acute triangle, all angle are less than 90°, so all
angles are acute angles.
°
angles are acute angles.
(ii) Right triangle: A right triangle has one angle measure 90° in angle.

15. (iii) Obtuse triangle: An obtuse triangle has one
angle that is bigger than 90 degrees.

16. Therefore:
 A trianglecannot have more than one right
angle:
 A triangle cannot have more thanone
obtuseangle:obtuseangle:
 In a rightangled Triangle, the sum of two
acute angle is90°.