That depends on what type of triangle is if the side given is equal to the perimeter divided by 3 then it is an equilateral triangle.
You cannot. For a given area, an equilateral triangle will have the smallest perimeter but that perimeter can be increased - without limit - without increasing the area.
count the grids
Measure it or use trigonometry if the 'included' angle is given.
It is: perimeter minus hypotenus+base = height Area = 0.5*base*height
That depends on what type of triangle is if the side given is equal to the perimeter divided by 3 then it is an equilateral triangle.
If you have the length of each of the three sides of a triangle, you can find the perimeter of (the distance around) the triangle by adding the length of the sides. Their sum will be the perimeter of this geometric shape.
You cannot. For a given area, an equilateral triangle will have the smallest perimeter but that perimeter can be increased - without limit - without increasing the area.
count the grids
If the triangle is equilateral, you simply divide the perimeter by three to find the length of each side. If the triangle is not equilateral, you will need more information to determine the length of each side.
The perimeter of a triangle is the distance around it. Add the lengths of the three sides to find the perimeter.
Measure it or use trigonometry if the 'included' angle is given.
There is no reason for the perimeter of a triangle to have any relation to the perimeter of an unrelated rectangle!
If you know the perimeter, there is no need to find it again.
You find the perimeter of a triangle by adding all the sides. There is no special rule for finding the perimeter.
how to find the perimeter of a right angled triangle using the area
One can't. The angle between those is needed.