Home > Documents > Use isosceles and equilateral triangles

# Use isosceles and equilateral triangles

Date post: 15-Mar-2016
Category:
Author: dale-pittman
View: 68 times
Description:
Use isosceles and equilateral triangles. CH 4.7. In this section…. We will use the facts that we know about isosceles and equilateral triangles to solve for missing sides or angles. What do you know about an isosceles triangle?. - PowerPoint PPT Presentation
Embed Size (px)
Popular Tags:

#### congruent segments

of 19 /19
CH 4.7 USE ISOSCELES AND EQUILATERAL TRIANGLES
Transcript
• CH 4.7USE ISOSCELES AND EQUILATERAL TRIANGLES

• In this sectionWe will use the facts that we know about isosceles and equilateral triangles to solve for missing sides or angles.

• What do you know about an isosceles triangle?There are two congruent sides in an isosceles triangle and two congruent angles.

• What do you remember about an equilateral triangle?All of the sides and angles should be congruent.The angles in an equilateral triangle always equal 60o.

• Base Angles TheoremIf two sides of a triangle are congruent, then the base angles are also congruent.Base angles are the angles at the ends of the 2 congruent segments.So, in the diagram angles B and C are congruent.Base angle Base angle

• Converse to the Base Angles TheoremIf two angles in a triangle are congruent, then the triangle is an isosceles triangle.

That means that the 2 sides of the triangles are also congruent.

• Find the value of x.This is an isosceles triangle, so the 2 sides are congruent5x + 5 = 355x = 30x = 6

• This is an isosceles triangle, so the 2 angles are congruent9x = 72x = 8

• x + x + 102 = 1802x + 102 = 1802x = 78x = 39

• The sum of the interior angles is 180x + 7 = 55x = 4855 + 55 + y = 180110 + y = 180y = 170

• If this is an isosceles triangle then what are the two congruent anglesx = 459y = 45y = 5

• How would you find the values of x and y?

• What are all of the missing angles?

• Page 267, #3 6, 14 - 22

Recommended