Lesson Plan
Illustrative Mathematics

Illustrative Mathematics: A ced.a.1: Sum of Angles in a Polygon

For Teachers 9th - 10th
This problem provides students with an opportunity to discover algebraic structure in a geometric context. They will divide up polygons into triangles. The will use the sum of the angles of 180 degrees for each triangle. Aligns with...
Unit Plan
Cuemath

Cuemath: Triangles

For Students 5th - 8th Standards
Explore everything about triangles. Learn about the different types, important properties, and how to find its area and perimeter. Check out the solved examples and interactive questions for better understanding.
Lesson Plan
Illustrative Mathematics

Illustrative Mathematics: 8.g Find the Angle

For Teachers 8th Standards
In this task, 8th graders have to reason with angles and angle measurements, including the sum of the angles in a triangle, to deduce information from a picture. Includes a GeoGebra worksheet that the teacher can use for demonstration...
Unit Plan
Mathigon

Mathigon: Geometry: Angles and Polygons: Drawing Triangles

For Students 9th - 10th Standards
This lesson focuses on the Triangle Inequality, when the sum of the lengths of any two sides of a triangle is greater than the length of the third. When this happens, the three sides cannot form a triangle.
eBook
Mathigon

Mathigon: Geometry: Triangles and Trigonometry: Pythagoras' Theorem

For Students 9th - 10th Standards
Pythagoras' Theorem: In any right-angled triangle, the square of the length of the hypotenuse (the side that lies opposite the right angle) is equal to the sum of the squares of the other two sides. (A+B=C)