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 cm2
- 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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