# Area

### Area for Triangle

Most basic formula since a triangle is a rectangle in half. $A=2b⋅h $

$A=21 absinC$

If we know the length of all three sides, we can use *Heron’s Formula*:
$s=21 (a+b+c)$
$A=s(s−a)(s−b)(s−c) $

### Area for Parallelogram

$A=b⋅h$ Also see Calculate with vectors

### Area for Circle

$A=πr_{2}$

Sector of a Circle $A=21 r_{2}θ$

### Area for Ellipse

$A=πab$

### Area of Irregular Plane

We divide into several areas. We cut it in several things