If m∠DCE = 84°, and m∠EBF = 62°, then the correct statements include;
a. m∠DEF = 34°.
b. m∠EDF = 62°
d. m∠DFA = 62°
e. m∠EDA = 96°
f. m∠DEB = 118°.
In Mathematics and Geometry, the triangle midpoint theorem states that the line segment which joins the midpoints of two (2) sides of a triangle is parallel to the third side, and it's congruent to one-half of the third side.
Based on the diagram, points D, E, and F are the midpoint of sides AC, BC, and AB respectively. By the midpoint theorem, we have the following parallel sides;
AC ║ EF
DE ║ AB
BC ║ DF
So, quadrilaterals DEFB and DAFE are parallelograms with congruent opposite (adjacent) angles;
m∠DAF ≅ m∠DEF
m∠EDF ≅ m∠EFB = 62°
By the triangle sum property, we have;
m∠DAF + m∠EBF + m∠DCE = 180°
m∠DAF = 180° - (84° + 62°)
m∠DAF ≅ m∠DEF = 34°.
Based on the corresponding angles theorem, we have these congruent angles;
m∠DFA ≅ m∠CED ≅ m∠EBF = 62°.
m∠DAF ≅ m∠CDE ≅ m∠EFB = 34°.
In triangle ADF, we have:
m∠DAF + m∠ADF + m∠DFA = 180°
m∠ADF = 180° - (34° + 62°)
m∠ADF = 84°.
Based on the consecutive interior angles theorem, we have;
m∠DEB + m∠EBF = 180°
m∠DEB = 180° - 62°
m∠DEB = 118°
Based on the linear pairs theorem, we have;
m∠CDE + m∠EDA = 180°
m∠EDA = 180° - 34°
m∠EDA = 146°