Take a point $A$ on $X$-axis and $B$ on $Y$-axis and find area of the triangle $AOB$. 

Let $A\left(x_1,y_1\right), B\left(x_2,y_2\right), C\left(x_3,y_3\right)$. Then, find the area of the $△ABC$.

Let $A\left(x_1,y_1\right), B\left(x_2,y_2\right), C\left(x_3,y_3\right)$. Then, find the area of the $△ABC$.

Let $A\left(x_1,y_1\right), B\left(x_2,y_2\right), C\left(x_3,y_3\right)$. Then, find the area of the $△ABC$.

Let $A\left(x_1,y_1\right), B\left(x_2,y_2\right), C\left(x_3,y_3\right)$. Then, find the area of the $△ABC$.

Find the area of the square formed by $\left(0,-1\right),\left(2,1\right),\left(0,3\right)$ and $\left(-2,1\right)$ taken inorder as vertices.

Find the area of the triangle formed by the following points $\left(2,0\right),\left(1,2\right),\left(1,6\right)$