Two-dimensional (2D) shapes are completely flat. They have two dimensions – length and width. A polygon is a closed 2D shape with straight sides that meet at vertices. Polygons can be regular or ...

A scalene triangle has 3 sides of different lengths and 3 unequal angles. An isosceles triangle has 2 sides of equal length. The dashes on the lines show they are equal in length. The angles at the ...

On the video, the rapper known as 2 Pi reels off rhymes as teenagers in classrooms and hallways sway and bop to the music. It's upbeat. It's catchy. It's . . . math. We solve triangles one by one We ...