How many triangles in a 50 sided shape?

By looking at other polygons with less sides, we can see how many triangles they can fit.

In a 4-sided polygon (square), you can fit 2 triangles.

In a 5-sided polygon (pentagon), you can fit 3 triangles.

In a 6-sided polygon (hexagon), you can fit 4 triangles.

In an 8-sided polygon (octagon), you can fit 6 triangles.

The pattern here is the number of triangles is equal to the number of sides minus 2.

T = N - 2

So... 50 - 2 = 48. 48 triangles can fit into a 50-sided polygon.