Area and perimeter of triangles

What you'll learn

1. Compute the perimeter of any triangle given its three side lengths
2. Apply the area formula A = 1/2 * base * height to right triangles and general triangles, correctly identifying the perpendicular height
3. Find the height of a triangle using the Pythagorean theorem when the height is not directly provided (e.g., in isosceles or equilateral triangles)
4. Use the equilateral triangle shortcuts: h = ssqrt3/2 and A = s^2sqrt3/4
5. Compute the area of a triangle from vertex coordinates using the shoelace formula or rectangle-decomposition method

Prerequisites

• Classification by sides and angles
• Pythagorean theorem