In a triangle $\triangle ABC, \angle A = 50^o, \angle B = 60^o$ and $\angle C = 70^o$. Find the measures of the angles of the triangle formed by joining the mid-points of the sides of this triangle.
Given:
In a triangle $\triangle ABC, \angle A = 50^o, \angle B = 60^o$ and $\angle C = 70^o$.
To do:
We have to find the measures of the angles of the triangle formed by joining the mid-points of the sides of this triangle.
Solution:
Let $D, E$ and $F$ are the mid points of sides $BC, CA$ and $AB$ respectively.
$DE, EF$ and $ED$ are joined.
This implies,
$EF \parallel BC$
$DE \parallel AB$
$FD \parallel AC$
Therefore,
$BDEF$ and $CDEF$ are parallelograms.
This implies,
$\angle B = \angle E = 60^o$
$\angle C = \angle F = 70^o$
$\Rightarrow \angle A = \angle D = 50^o$
Hence, $\angle D = 50^o, \angle E = 60^o$ and $\angle F = 70^o$.
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