Theory:

Area of a triangle: To obtain the area of a triangle multiply the base by the height and then divide by \(2\).
Area.png
 
\(Area (A) = 1/2(b × h)\) or \(b × h / 2\)
Thus, the height of the triangle \(h = Area × 2 / b\)
And, the base of triangle \(b = Area × 2 / h\)
Where \(h\) is denoted as height.
Where \(b\) is denoted as base.
 
The perimeter of a triangle: To obtain the perimeter of a triangle, add the lengths of each of its \(3\) sides.
perimeter.png
 
\(Perimeter (P) = AB + BC + CA\).
\(Perimeter (P) = a + b + c\).
Where \(a, b, c\) is denoted as the length of three sides.