Theorem:
In any triangle ABC, prove that the area of a triangle ABC is given by

Proof:

Let ABC be any triangle. Draw AD perpendicular to BC (CB produced if necessary), so that AD = h
In figure (i), we have


Similarly, we have
Area of a triangle |
In any triangle ABC, prove that the area of a triangle ABC is given by


Let ABC be any triangle. Draw AD perpendicular to BC (CB produced if necessary), so that AD = h
In figure (i), we have


Similarly, we have
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