but moment is force by distance rite

but u doin the moment of the area diagram so it wud be area x by the centroidal distance for that triangle its l+b /3 and well the fixed end moments diagram it wud be a trapizium which the centroid distance is 2 ma + mb / ma +mb x l/3 look up the centroid of a trapezium

Shape Figure Area

Triangular area

Quarter-circular area

Semicircular area

Quarter-elliptical area

Semielliptical area

Semiparabolic area The area between the curve and the

axis, from to

Parabolic area The area between the curve and the line

Parabolic spandrel The area between the curve and the

axis, from to

General spandrel The area between the curve and the

axis, from to

Circular sector

The area between the curve (in polar coordinates) and the pole, from to

Circular segment

Quarter-circular arc

The points on the circle and in the first quadrant

Semicircular arc

The points on the circle and above the axis

Arc of circle

The points on the curve (in polar coordinates) , from to