- The middle triangle looks equilateral.
- The two outside triangles are congruent.
- The two outside triangles could equal the middle triangle.
- There are a total of five vertices.
- There are two obtuse triangles on the outside.
- The angles on the base of the triangle are supplementary.
- The large triangle is isosceles.
- The baselengths of the three smallest triangles add up to the baselength of the large triangle.
- The two end triangles are scalene.
- Angles in a triangle add up to 180°.
- There are three small triangles and one large triangle.
- Actually, there are six triangles.
- The whole shape can be made from just two triangles. (
*Do you see it?*) - The angles of the overlapping triangles are right angles.

- The middle triangle looks equilateral.
**False.** - The two outside triangles are congruent.
**True, we can use Side Side Side.** - The two outside triangles could equal the middle triangle.
**False.** - There are a total of five vertices.
**True by observation.** - There are two obtuse triangles on the outside.
**True, we can use the converse of the Pythagorean Theorem.** - The angles on the base of the triangle are supplementary.
**True by linear pair.** - The large triangle is isosceles.
**True.** - The baselengths of the three smallest triangles add up to the baselength of the large triangle.
**True by observation.** - The two end triangles are scalene.
**True.** - Angles in a triangle add up to 180°.
**True always.** - There are three small triangles and one large triangle.
**True.** - Actually, there are six triangles.
**Also True.** - The whole shape can be made from just two triangles. (
*Do you see it?*)**True!** - The angles of the overlapping triangles are right angles.
**Awesome observation! Let's look into that!**

We can use the Pythagorean Theorem to see that $$15^2+20^2=(18+7)^2.$$ The orange triangle is a right triangle! Now we can use SOHCAHTOA to find the other angles! $$x=\tan ^{-1}(\frac {15}{20})=36.87\deg$$ $$y=\tan ^{-1}(\frac {20}{15})=53.13\deg.$$

Did you get all that?