Triangles1st year

P26

Chapter 4

Triangle

• All 3 angles of a triangle must add up to 180 degrees

• There are 3 types of triangles• Equilateral

• Isosceles

• Scalene

3 different types of Triangles

• Equilateral• All sides are the same

Length and angles are 60 degrees

3 different types of Triangles

• Isosceles • 2 sides are the

same length

3 different types of Triangles

• Scalene • All 3 sides different lengths

Angles are all different sizes

How to construct an equilateral Triangle

Draw base line at given measurement.

Either end of the line draw lines up at 60 degrees. Where they meet is the vertex

V

How to draw an Isosceles Triangle

What do we know????

2 sides are equal in length and 2 base angles are the same angle.

Use vertically opposite angles to work out base angle

Vertically opposite angle means the angle above the point is equal to the angle below

70

There if all angles of a triangle equal 180 degrees 180 - 70 110 ÷ 2 = 55

Base angles are 55 degrees each

Questions

Exam Practice