The area of a triangle could be determined using the following formula
[tex]\boxed{a= \frac{1}{2} \times b \times h}[/tex]
plug in the numbers
[tex]a = \frac{1}{2} \times 21 \times 12 [/tex]
[tex]a = \frac{1}{2} \times 252[/tex]
[tex]a= \frac{252}{2} [/tex]
a = 126
The area of the triangle is 126 square meters
