Prove that area of a triangle = X base X altitude.

Question

Philoid · Accepted Answer

We know that when a parallelogram and a triangle lie on same base and between same parallel lines then, area of the triangle is half the area of the parallelogram.

Consider the figure,

Here,

Area(ΔABF) = 1/2 Area(||gm ABCD) (From above statement) –1

Area(||gm ABCD) = Base× Height –2

Sub –2 in –1

Area(ΔABF) = 1/2 × Base× Height