These are two shape-related ideas from GCSE Maths:
Two shapes are said to be congruent if the number and lengths of their sides are the same (although they can be rotations or reflections of each other). For example, two triangles that both have sides of length 3, 4 and 5 would be congruent.
Two shapes are said to be similar if one is an enlargement of the other - i.e. they have the same number of sides and the lengths of one share a multiple with the lengths for the other. For example, a triangle with sides 3, 4, 5 and a triangle with sides 6, 8, 10 are similar because the sides in the latter are all twice as long as those in the former.
Note that shapes that are congruent are also similar.
Your Task
Approach these tasks in numerical order and go as far as you are comfortable with:
ask the user to enter the lengths of the sides of two triangles
check whether the two triangles are congruent and display the verdict
check whether the two triangles are similar and display the verdict
ensure that your program works with the lengths entered in any order
generalise your program to work with shapes with any numbers of sides
check that both shapes have the same number of sides
validate the input to check that all values are numbers