# LESSON 4-8 PROBLEM SOLVING ISOSCELES AND EQUILATERAL TRIANGLES

So we know that this angle right over here is also 31 degrees. And then we can subtract 90 from both sides. Published by Francis Manning Modified over 3 years ago. This is one base angle. BC has the same length as CD. The side opposite the vertex angle is called the base, and the base angles are the two angles that have the base as a side.

So that angle plus is going to be equal to Using Properties of Equilateral Triangles Find the value of x. Using Properties of Equilateral Triangles Find the value of y. Now, this angle is one of the base angles for triangle BCD. So it’s an equilateral triangle, which means all of the angles are equal. A triangle with two congruent sides.

And once again, these two angles plus this angle right over here are going to have to add up to degrees. So first of all, we see that triangle ABC is isosceles.

So we have a bunch of congruent segments here.

Name the parts of. So that angle plus is going to be equal to Don’t I need to know two other sides? We think you have liked this presentation. And the trick here is like, wait, how do I figure out one side of a triangle if I only know one other side? You get the measure of angle BCD is equal to– let’s see.

# Isosceles & equilateral triangles problems (video) | Khan Academy

Subtract 36 solvign both sides, we get 2x– that 2 looks a little bit funny. You can kind of imagine it was turned upside down. And we need to figure out this orange angle right over here and this blue angle right over here. So this right over here is 62 degrees.

## 4-8 Isosceles and Equilateral Triangles Lesson Presentation

This is degrees. Angle ABE equilsteral going to be 60 plus 45, which is degrees. My presentations Profile Feedback Log out. And we are done. This is the other base angle. And then we’re done because angle ABE is going to proble, equal to the 60 degrees plus the 45 degrees. You’ve got x plus x plus 90 is going to be degrees. And then finally, if you want to figure out this blue angle, the blue angle plus these two degree angles are going to have to add up to degrees.

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Every isosceles triangle is equilateral. About project Prolbem Terms of Service. To log in and use all the features of Khan Academy, please enable JavaScript in your browser. So the two base angles are going to be congruent.

equiilateral You call that an x. These two characters– let’s see. Well, that’s part of angle ABE, but we have to figure out this other part right over here. Corresponding angles in congruent triangles. So you get 2x plus– let me just write it out. So you get 62 plus 62 plus the blue angle, which is the measure of angle BCD, is going to have to be equal to degrees. We have x plus x plus 90 is ewuilateral to be equal to degrees.

We get 2x is equal to– minus 30 is Definitions – Review Define an isosceles triangle. And the vertex angle right here is 90 degrees. The two x’s, when you add them up, you get 2x.