Plane figures include triangle, circle, square, rectangle, and parallelogram.

1. Triangle

Perimeter: a + b + c

Area: 1/2 × bh

2. Circle

Circumference: 2πr

Area: πr2

3. Square

Perimeter: 4a

Area: a2

4. Rectangle

Perimeter: 2(l + b)

Area: l × b

5. Parallelogram

Perimeter: 2(a + b)

Area: bh