8.1.10.2 Triangle Plus One
- Author:
- jennifer.r.peter, elishevacarl
- Topic:
- Geometry, Mathematics
Let’s use reasoning about rigid transformations to find measurements without measuring.
Spend time exploring the tools bar and see what occurs. Select points, angles, line segments, and the entire triangle. Try to locate the tools for rotating, reflecting, translating the triangle.
Draw the midpoint of side AC
2. Use the rotate tool 
Rotate triangle ABC 180 degrees using center b to form triangle C'B'A'.
What does your figure look like?
Check your work here!
What kind of quadrilateral is ABCD? Explain how you know.
Look back at the triangle as it is rotated.
What happens to points and under a rotation?
Look at the new polygon made as a result of the rotation.
How do you know that the lines containing opposite sides of ABCDare parallel?
Compare the area of triangle ABC to the area of polygon ABCD.
How is the area of parallelogram ABCD related to the area of triangle ABC?
Triangle plus Two
The picture shows 3 triangles. Triangle 2 and Triangle 3 are images of Triangle 1 under rigid transformations.
Triangle plus Two
The picture shows 3 triangles. Triangle 2 and Triangle 3 are images of Triangle 1 under rigid transformations.
Triangle plus Two: Side Length Exploration
The picture shows 3 triangles. Triangle 2 and Triangle 3 are images of Triangle 1 under rigid transformations.
Triangle plus Two: Angle Exploration
The picture shows 3 triangles. Triangle 2 and Triangle 3 are images of Triangle 1 under rigid transformations.