Answer:
Option A. 68.4 square units.
Step-by-step explanation:
Since sides ED = EF = 13 units
So the given triangle is an isosceles triangle and in an isosceles triangle EFD, perpendicular drawn from E to DF, will be perpendicular bisector of DF.
Moreover, to this perpendicular bisector to DF will be the height of the triangle.
Now Area of a triangle of [tex]\frac{1}{2}[/tex] × base × height.
Sin 63 = [tex]\frac{Height}{Hypotenuse}[/tex] = [tex]\frac{h}{13}[/tex]
h = 13 sin 63 = 13 ( 0.891) = 11.583 units
Cos 63 = [tex]\frac{Base}{Hypotenuse}[/tex] = [tex]\frac{Base}{13}[/tex]
Base = 13 cos 63 = 13 × (0.454)
= 5.90 units
Since DF = 2 × base = 2 × 5.90
= 11.80 units
Now area of EDF = [tex]\frac{1}{2}[/tex] × 11.80 × 11.583
= 68.86 ≈ 68.40 square units.
Option A. 68.4 square units.
