Area

Area for Triangle

Most basic formula since a triangle is a rectangle in half. $A=\frac{b\cdot h}{2}$

$A=\frac{1}{2}ab\sin C$

If we know the length of all three sides, we can use Heron’s Formula: $s=\frac{1}{2}(a+b+c)$ $A=\sqrt{s(s-a)(s-b)(s-c)}$

Area for Parallelogram

$A=b\cdot h$ Also see Calculate with vectors

Area for Circle

$A=\pi r^2$

Sector of a Circle $A=\frac{1}{2}{r}^2\theta$

Area for Ellipse

$A=\pi ab$

Area of Irregular Plane

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

Related

• Volume