∆ABC and ∆DEF are equilateral triangles A(∆ABC) : A(DEF) = 1.2. if AB = 4 then what is length of DE? ❎No Spam
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Answered by
3
Answer:
Length of the side DE is 4√2
Step-by-step explanation:
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Answered by
48
Answer:
4√2
Step-by-step explanation:
Given that ∆ABC and ∆DEF are equilateral triangles A(∆ABC) : A(DEF) = 1.2. if AB = 4.
Draw a line perpendicular X and Y in both ∆ABC and DEF.
Now,
In ∆ABX and ∆DEY (equilateral triangle)
/_B = /_C = 90°
/_AXB = /_DYE (by construction)
∆ABX ~ ∆DYE
Therefore,
AB/DE = AX/DY (corresponding sides of similar triangle)
(Ar. ∆ ABC)/(Ar. ∆DEF) = 1/2
(1/2 × b × h)/(1/2 × b × h) =1/2
(1/2 × AB × AX)/(1/2 × DE × DY) = 1/2
(1/2 × 2AB²)/(1/2 × DE²) = 1/2
As, AB/DE = AX/DY
So,
(AB²)/(DE²) = 1/2
(4)²/(DE²) = 1/2
16/DE² = 1/2
DE² = 32
DE = 4√2
Therefore, the length of DE is 4√2
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