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3.5 Area Of Triangles
Let D stands for the area of triangle.
Let b = base and h = height then D =
1/2 bh.
For finding the area of a triangle (D
) three types of additonal formulas are used. They are -
SSS Type : If a, b and c are lengths of
sides of triangle and s = ABC and s = 
i.e. semiperimeter, then
Area of triangle ABC ( D)
= 
This formula is a contribution to mathematics by a famous Greek
philosopher and mathematician, Heron (or Hero). Therefore this is
known as “Hero’s formula”.
We have, Area of D ABC = 
bc sin A.
But sin A = 2 sin A / 2 cos A / 2 (see half angles).
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