# In a triangle ABC, angle A=40o,, angle B=80o, angle C=60o. Find the measures of the angles of the angles of the triangles formed by joining the midpoints of this triangle. Please answer fast my worksheet is due on monday!!

Dear Student! Given : ABC is a triangle with ∠A = 40°, ∠B = 80°, ∠C = 60°.

Let D, E, F be the mid points of side BC, AC, AB respectively.

Now according to mid point theorem, The line segments joining the mid points of the sides of a triangle is parallel to the third side of triangle.

⇒ FE // BC

⇒ FE // BD and FE // DC  ..... (1)

ED // AB

⇒ ED // AF and ED // FB  ..... (2)

FD // AC

⇒ FD // AE and FD // EC  ..... (3)

from (1), (2) and (3) we can conclude that

AFDE, BFED, DFEC are parallelogram.

Also opposite angles of a parallelogram are equal

⇒ ∠FAE = ∠FDE = 40°

⇒ ∠FBD = ∠FED = 80°

⇒ ∠DCE = ∠DFE = 60°

∴ In ΔDEF

∠D = 40°, ∠E = 80° and ∠F = 60°

Cheers!

• 30

d is the mid point of bc;

e is mid point of ac ;

&  f is mid point ofab;

then angle d is 40; e is 80 ; f is 60

• -11

d=40      e=80          f=60

• -13
What are you looking for?