Answer:
a. 72°
b. side DF
Explanation:
The base angles of an isosceles triangle are congruent and equal to the complement of half the a.pex angle. The shortest side of the triangle is opposite the smallest angle.
a.
∠F = 90° -(36°/2) = 72°
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b.
The smallest angle is 36°. The side opposite that angle is side DF.
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Additional comment
The relation we used to find the base angle is based on the fact that the sum of angles in a triangle is 180°. For angle F, with D = F, we have ...
D +F +36° = 180°
2F = 180° -36° . . . . . . substitute D = F, and subtract 36°
F = 90° -(36°/2) . . . . . divide by 2