Area of Plane Figures

- Area of a triangle:
- Area of a triangle =
- All the congruent triangles are equal in area, but the triangles having equal areas may or may not be congruent.

**Example:** ΔABC is isosceles with AC = BC = 6 cm. AE and BD are the medians and AF = 4 cm. What is the area of ΔABD?

**Solution:** In ΔABE and ΔBAD, we have

BE = AD ]

∠ABE = ∠BAD [Angles opposite to equal sides]

AB = AB [Common]

⇒ ΔABE ΔBAD [By SAS congruency criterion]

Area (ΔABE) = Area (ΔBAD)

Now, Area ΔABE =

⇒ Area ΔABD = 6 cm^{2}

**Area of triangle using Heron's formula:**

When all the three sides of a triangle are given, its area can be calcula…

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