Triangular Beam

Problem 574
In the beam section shown in Fig. P-574, prove that the maximum horizontal shearing stress occurs at layers h/8 above or below the NA.
 

Problem 573
The cross-section of a beam is an isosceles triangle with vertex uppermost, of altitude h and base b. If V is the vertical shear, show that the maximum shearing stress is 3V / bh located at the midpoint of the altitude.