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Lesson 5: Constructing triangles

# Construct a right isosceles triangle

Can you build a triangle that is both a right triangle and an isosceles triangle? Created by Sal Khan.

## Want to join the conversation?

• unique triangle.. what about reflected triangles? they would have the same lengths! • If you had a quadrilateral for which you knew all 4 sides, have you uniquely determined it? Are there other quadrilaterals with the same 4 sides but different angles? • I am having a lot of trouble on this topic... could you please add maybe another problem in this video? • How do i make a right triangle wth sides 5,8,and 10 • don't have uestions  • unique triangle.. what about reflected triangles? they would have the same lengths! • Can someone explain me one a few things here because I didn't really understand much. like what if you need to make a 80 degree triangle with a 9 inch side? how am I supposed to find out if it even can be made or if its not a unique triangle? I'm bad at making triangles for math so I need some help to figure out how to know. I feel like this is a stupid question. (T-T) • If it is a right isosceles triangle, you would first make the 90 degree angle. Then you would drag the other two points until the side across from the 90 degree angle is 9 inches and the other two sides are equal.
If you are making an isosceles triangle with just a 80 degree corner and no 90, then you would first make the 9 inch side, then drag the corner across from it until it is 80 degrees, then make the last two sides of the triangle equal.
Hope this helps!
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