# Trapezoid

## Perimeter

$$P=a+b+c+d$$

## Area

$$A=m\xb7h$$

## Midsegment

$$m=\frac{a+c}{2}$$

# Spetial Trapezoids - Isosceles Trapezoids

# - Tangent Quadrilateral

$$a+b=2c$$

Attention! Not all isosceles trapezoids are tangent quadrilaterals!

## Area with the radius of the inscribed circle

$$s=\frac{a+b+2c}{4}$$

$$A=s\xb7r$$

# Spetial Trapezoids - Isosceles Trapezoids - Cyclic

# Quadrilateral

$${d}^{2}=a\xb7b+{c}^{2}$$

Attention! All isosceles trapezoids are also cyclic quadrilaterals!

## Area with the radius of the circumscribed circle

$$A=\frac{d\xb7c\xb7\left(a+c\right)}{4R}$$

Keywords: trapezoid, perimeter, area