Mensuration in 2-D (Two-dimensional) refers to the study of measurement of different geometric shapes in a plane, such as triangles, circles, squares, rectangles, and polygons. It involves calculating various parameters such as area, perimeter, and sometimes diagonals, based on the shape and its dimensions.
Here are some important concepts in 2-D mensuration:

NOTE:
A scalene triangle is a type of triangle where all three sides have different lengths and all three angles have different measures. It does not have any equal sides or angles, distinguishing it from other types of triangles like isosceles (two equal sides) and equilateral (three equal sides).