
# 10.1: Plane

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Area (A) is measured in square units, perimeter (P) is measured in units, and circumference (C) is measured in units.

#### Square

$P=4 s$

$A=s^{2}$

#### Rectangle

$P=2 l+2 w$

$A=l w$

#### Parallelogram

$P=2 a+2 b$

$A=b h$

#### Trapezoid

$P=a+b+c+d$

$A=\frac{1}{2} h(a+b)$

#### Triangle

$P=a+b+c$

$A=\frac{1}{2} b h$

#### Circle

$C=2 \pi$

$r=\pi r^{2}$