The mid-point of the sides of a triangle along with any of the vertices as the fourth point make a parallelogram of area equal to
(A)
(B)
(C)
(D)
Answer: [A]
Solution.
Let the given triangle ABC be shown as below with medians AE, BF, CD.
D is the mid-point of AB, E is the mid-point of BC, F is the mid-point of AC
Mid-point theorem states that the line segment in a triangle joining the midpoint of two sides of the triangle is said to be parallel to its third side and is also half of the length of the third side
So,
DF = BE = EC …(i)
DE = AF = FC …(ii)
FE = AD = DB …(iii)
In and
AD = FE (from iii)
DF = EC (from i)
AF = FC (given)
(SSS congruence)
Similarly we can prove that,
So the bigger triangle is divided into 4 smaller congruent triangles.
So area of (area of one smaller triangle) …(iv)
If we consider the parallelograms formed then we can see that one consists of two such triangles.
So area of every (area of one smaller triangle) …(v)
Using (iv) and (v),
area of every
Therefore option (A) is correct.