# Finding Area

#### See below for helpful information about finding the area of squares, rectangles, parallelograms, circles, ellipses, trapezoids, and triangles.

### Square

A = a^{2}, in which *a* is one of the sides.

### Rectangle

A = ab, in which *a* is the base and *b* is the length.

### Parallelogram

A = bh, in which *b* is the base and *h* is the height.

### Circle

A = πr^{2}, in which π is 3.1416 and *r* is the radius.

### Ellipse

A = πr_{1}r_{2}, in which π is 3.1416, *r*_{1} is the longer radius, and *r*_{2} is the shorter radius.

### Trapezoid

A = (h[b_{1} + b_{2}])/2, in which *h* is the height, *b*_{1} is the longer parallel side, and *b*_{2} is the shorter parallel side.

### Triangle

**Given base and height:** A = (1/2)bh, in which b is the base and h is the height.

**Given side, angle, side (SAS):** (1/2) ab x sinθ, in which *a* is one side, *b* is another side, and θ is the known angle.

**Given three sides:** when s = (a + b + c)/2 *(Heron's formula)*, in which *a, b,* and *c* represent the three sides.