Welcome to Geometry Fundamentals! In this course, you'll explore geometry and master challenging geometric problem-solving techniques.

There won't be a lot of formulas. Instead, you'll focus on strengthening your foundational geometric reasoning skills and intuition.

Memorizing formulas is a poor substitute for learning to use your own reasoning and intuition.

This course will cover a lot of ground. After reviewing some basics...

...the techniques in this course will quickly diversify. You'll need to use strategic, mathematical thinking, not a ruler, to solve each challenge.

And instead of memorizing a formula to calculate the lengths and areas of just the simplest shapes, you'll build intuition for how to simplify shapes you've never seen before...

...and then more easily calculate that shape's measurements.

If each side of both the triangle and regular hexagon is $3 \text{ cm}$ long, what is the longest distance across the hexagon?

*The sliders below the figure let you move the triangle.*

*small*, shaded triangles?

**perimeter**, of the shaded shape?

Each of these three rectangles measures $3 \text{ cm}$ by $1 \text{ cm,}$ and **the sliders below the figure let you move two of the rectangles.**

Join the three rectangles into a single figure using the motions that the sliders allow, to make a shape with the **smallest possible perimeter.** What is the length of that perimeter?

*completely* around each of the nine circles in the design below is $4 \text{ m}.$ What is the total length of the dark, meandering path in the figure?