a.)First Moment-Area Theorem
The angle between the tangents, denoted
, is equal to the difference between 
and 
First moment-area theorem: The angle between the tangents to the deflection curve at two points A and B is equal to the area of the M/EI diagram between those points.
b.)Second Moment-Area Theorem
Second moment-area theorem: The tangential deviation 
of point B from the tangent at point A is equal to the first moment of the area of the M/EI diagram between A and B, evaluated with respect to B.
The first moment of the area of the M/EI diagram can be obtained by taking the product of the area of the diagram and the distance 
from point B to the centroid C of the area
