Answer:
The measure of angle F is m∠F=130°
Step-by-step explanation:
step 1
Find the measure of angle E
we know that
An isosceles triangle has two equal sides and two equal interior angles
In this problem
DF=EF ----> given problem
so
Triangle DEF is an isosceles triangle
m∠D=m∠E
we have
m∠D=25°
substitute
m∠E=25°
step 2
Find the measure of angle F
we know that
The sum of the measures of the interior angles in a triangle must be equal to 180 degrees
so
m∠D+m∠E+m∠F=180°
substitute the values
25°+25°+m∠F=180°
50°+m∠F=180°
m∠F=180°-50°
m∠F=130°
