# Centroids of Plane Areas

## Square, rectangle, cirle. semi-circle and right-angled triangle

The **centroid** of an area is the **point** where the whole area is considered to be concentrated.

### Square

#### Distance

*x = a / 2 (1a)*

*y = a / 2 (1b)*

#### Area

*A = a ^{2} (1c)*

### Rectangle

#### Distance

*x = a / 2 (2a)*

*y = b / 2 (2b)*

#### Area

*A = a b (2c)*

### Circle

#### Distance

*x = r (3a)*

*y = r (3b)*

#### Area

*A = π r ^{2} (3c)*

### Semi-Circle

#### Distance

*x = 4 r / (3 π) (4a)*

*y = r (4b)*

#### Area

*A = π r ^{2}/ 2 (4c)*

### Right-angled Triangle

#### Distance

*x = b / 3 (5a)*

*y = h / 2 (5b)*

#### Area

*A = b h / 2 (5c)*