Question

AD is perpendicular to the
base
​

Answer 1

We know that, AD is perpendicular to BC.

In ∆ABM, Height = AD (Perpendicular to line when BM is extended)

Area of triangle = 1/2 × base × height

Area of ∆ABM = 1/2 × BM × AD

HENCE PROVED

MARK AS BRAINLIEST