Properties of Triangles

Slides:

Advertisements

Similar presentations

Report by Jennifer Johnson

Advertisements

Warm Up Determine the measure of the missing interior angle. What type of triangle is it? Unit 8 - Lesson 2 Exterior Angles of a Triangle.

CH 4.7 USE ISOSCELES AND EQUILATERAL TRIANGLES. In this section… We will use the facts that we know about isosceles and equilateral triangles to solve.

Geometry 5 Level 1. Interior angles in a triangle.

Aim 6.4: To explore the exterior angles of a polygon

Applying Triangle Sum Properties

ANGLES IN TRIANGLES LESSON 16(3).

HOW TO FIND AN ANGLE MEASURE FOR A TRIANGLE WITH AN EXTENDED SIDE

Classify Triangles Standard 4C.

Adapted from Walch Education Isosceles triangles have at least two congruent sides, called legs. The angle created by the intersection of the legs is.

Triangles Isosceles & Fundamentals

4-6 Isosceles & Equilateral Triangles

Geometry. Kinds of triangles Geometry Kinds of triangles.

Classifying Triangles Angle Measures of Triangles.

Chapter 4.1 Notes: Apply Triangle Sum Properties Goal: You will classify triangles and find measures of their angles.

Types of 2 D Shapes and There Properties 1)A shape with 3 sides is called a triangle 2)A shape with 4 sides is called a quadrilateral 3)The general term.

Section 3-4: Parallel Lines and the Triangle Angle-Sum Theorem.

Triangle A polygon with three sides and three angles. A triangle can be names by its’ side lengths and angles. – Side lengths: isosceles, equilateral,

Triangle Classification. Objectives Classify triangles by their angle and side measures Find the sum of the measure of the interior and exterior angles.

Classify triangles by sides No congruent sides Scalene triangle At least two sides congruent Isosceles triangle Three congruent sides Equilateral triangle.

Polygons – Angles In Regular Polygons Regular Polygons have equal sides and equal angles, So if we can find one side, we would know the measure of all.

Goal, to classify triangles by their sides and by their angles.

1.2 Angle Relationships and similar triangles

4.3 ISOSCELES AND EQUILATERAL TRIANGLES. VOCABULARY Two angles of an isosceles triangle are always congruent. These are the angles opposite the congruent.

Triangle Congruence 4.5 Isosceles and Equilateral Triangles.

Triangles and Angles Classifying Triangles. Triangle Classification by Sides Equilateral 3 congruent sides Isosceles 2 congruent sides Scalene No congruent.

3.4.  The sum of the measures of the angles of a triangle is 180.

Triangles and Their Angles Geometry – Section 4.1.

Classify These Triangles by Sides and Angles. Chapter 4 Congruent Triangles Section 4.1: Triangle Sum Properties Todays Objective: Determine if a right.

Geometry Section 4.1 Apply Triangle Sum Properties.

Properties of Triangles

4.1 Triangle Angle Sum and Properties. How many degrees in a triangle? The sum of the angles in any triangle is exactly 180 degrees.

Applying Triangle Sum Properties

 Scalene Triangle No sides congruent  Isosceles Triangle Exactly 2 sides congruent  Equilateral Triangle All sides congruent.

Use isosceles and equilateral triangles

Isosceles Triangles.

Geometry 4.1 Triangle and Angles.

11-4 Exterior Angles of Triangles

Exterior Angles of Triangles

Types of Triangles and Their Properties

Angles In Triangles Types of Triangles Isosceles triangle

Chapter 4: Congruent Triangles

Properties of Triangles

Polygons – Angles In Regular Polygons

Angles In Triangles Types of Triangles Isosceles triangle

Warm-up Find x a) b).

Exterior Angles of Triangles

Inside angles theorem.

Warm-up Find x a) b).

Warm-up Find x a) b).

V L T The sum of the interior angles of a triangle is 180 degrees.

Parallel Lines, Transversals, Base Angles & Exterior Angles

ALWAYS add up to 360 degrees! No matter what polygon it is.

Use isosceles and equilateral triangles

Base Angles & Exterior Angles

Isosceles Triangles. Isosceles Triangles Base Angles If 2 angles in a triangle are congruent, then the sides opposite them are congruent.

Isosceles Triangles. Isosceles Triangles Base Angles If 2 angles in a triangle are congruent, then the sides opposite them are congruent.

Chapter 4: Triangles Classifying Triangles by sides:

3-3 Parallel Lines & the Triangle Angle Sum Theorem

Lesson 3: Introduction to Triangles

Unit 2: Properties of Angles and Triangles

Triangles Teacher Twins©2014.

Triangles Teacher Twins©2014.

Lesson 3-2 Isosceles Triangles.

Presentation transcript:

Properties of Triangles Objectives: G Grade Identify isosceles, equilateral and right-angled triangles. Use the word ‘congruent’ when triangles are identical. E Grade Show that the angles of a triangle add up to 180o and use this to find angles. Show that the exterior angle of a triangle is equal to the sum of the interior opposite angles. Use angle properties of isosceles, equilateral and right-angled triangles.

Properties of Triangles The external angle = a + c b c A B C When a side of a polygon is extended an exterior angle is created We know that the sum of internal angles (a + b + c) = 180o We also know that angles on a line add up to 180o Therefore if: a + c + b = 180o and b + external angle = 180o The external angle = a + c

Properties of Triangles Example 39o 81o y x x y x is an exterior angle so x = 39 + 81 = 120o 39o 81o x x is again an exterior angle so 120 = y + 90 so y = 30o

Properties of Triangles Now do these: c = 63 + 74 = 137o d = 180 - 63 = 113o e = 180 - 74 = 106o a = 42 + 40 = 82o b = 138 - 48 = 90o 132 = x + 90 x = 42o

Properties of Triangles Now do these: r = 140 - 32 = 108o 180 - 140 = 40o p = 49 + 63 = 112o 180 - 118 = 62o q = 49 + 76 = 125o s = 180 – (40 + 62) = 78o Bearing 131 + 180 =311o or 270 + 41 =311o x = 131 - 90 = 41o

Properties of Triangles Worksheet