Answer:
The measure of angle E is:
m∠E = 80°
Step-by-step explanation:
Given
The triangle ΔDEF
It is stated that DE=EF and G is the midpoint of EF.
It means the midpoint G has converted the triangle into two equal right-angles triangles ΔDEG and ΔDFG with the right-angle at G.
Given
m∠GDE = 10°
As the right-angle triangle, ΔDEG lies at the right-angle G.
So, m∠DGE = 90°
as
m∠GDE = 10°
m∠DGE = 90°
m∠E = ?
We know that the sum of angles of a triangle is 180°.
m∠GDE + m∠DGE + m∠E = 180°
10° + 90° + m∠E = 180°
100 + m∠E = 180°
m∠E = 180° - 100
m∠E = 80°
Therefore,
The measure of angle E is: m∠E = 80°
× 
≈ 