There are 3 ways to find the perimeter of a triangle -
1.Add the lengths of all three sides together to find the perimeter.
2.For a right (90º) triangle with two known side lengths: Label the longest side c and the other two a and b.Find the right triangle's third side using the Pythagorean Theorem: a² + b² = c².
3.For a triangle with two known side lengths and a known angle between them:Label the known angle D and the adjacent sides a and b. Label the unknown side c. Find the length of side c using the Law of Cosines: c² = a² + b² - 2abcos(D).
For area we have got two ways-
1. When base and height are know:area = 1/2 X b X h ( b = base; h = height )
2. When all 3 sides are known:name all 3 sides as a,b and c respectively. s = a+b+c/2.
area = √ s (s-a)(s-b)(s-c).
There are two other formulas for finding area which are trigonometry based.