Question

Two triangle on the same base (or equal bases) and between the same parallels are equal in area.

Answer 1

REF.Image

As perpendicular distance between two parallel line is constant at all points $\Rightarrow h_1=h_2$

As area of triangle = $\frac{1}{2}\times$ base $\times$ height $\Rightarrow$ it is same for both triangles.