Respuesta :

Answer:

[tex]28\sqrt{3}[/tex]

Step-by-step explanation:

The area of the big triangle is 1/2 b h =  1/2*6*(12^2 = 6^2 + x^2)

that ends up being [tex]\sqrt{108} = 36\sqrt{3}[/tex]

the small triangle are needs to be subtracted....

[tex]\frac{\left(4\cdot \:sin\left(90\right)\right)}{sin\left(30\right)}[/tex] that is the length of the unknown side...

1/2 B * h of that triangle get you to [tex]8\sqrt{3}[/tex]

just subtract the two areas

mathstudent55

Answer:

(B) 28√3

Step-by-step explanation:

The area of quadrilateral ABED is equal to the area of triangle CDE subtracted from the area of triangle ABC.

Area of triangle CDE:

Triangle ABC is equilateral. All sides have length 12.

AB = BC = AC = 12

BE = 8

BE + EC = BC

8 + EC = 12

EC = 4

In an equilateral triangle, all angles measure 60°.

m<C = 60°

m<CDE = 30°

Triangle CDE is a 30-60-90 triangle.

DE = EC√3

DE = 4√3

area of triangle CDE = bh/2

area of triangle CDE = (EC)(DE)/2

area of triangle CDE = (4)(4√3)/2

area of triangle CDE = 8√3

Area of triangle ABC:

Side AC is a base of triangle ABC.

AC = 12

(1/2)AC = 6

The altitude of triangle ABC from side AC to vertex B measures

h = 6√3

area of triangle ABC = bh/2

area of triangle ABC = (AC)(h)/2

area of triangle ABC = (12)(6√3)/2

area of triangle ABC = 36√3

area of quadrilateral ABED = area of triangle ABC - area of triangle CDE

area of quadrilateral ABED = 36√3 - 8√3

area of quadrilateral ABED = 28√3

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