here
height of the prism ( H )= 6m
area of a triangle ( A )= 1/2 × base × height
= 1/2 × 3 × 4
= 6 m^2
we know ,
volume of prism = H×A
= 6m × 6m^2
= 36 m^3
therefore volume of the prism is 36 m^3
