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The altitude AD of an equilateral triangle ABC of side length a is
A(a square root of 2) divided by 2
Ba divided by 2
C(a square root of 3) divided by 2
Da square root of 3
Answer & Solution
Correct answer: C. (a square root of 3) divided by 2
1. In equilateral triangle ABC of side a, altitude bisects the base.
2. Half-base = a/2; using Pythagoras, h squared = a squared minus (a/2) squared = 3 a squared / 4.
3. Hence altitude = (a square root of 3) / 2.
_Source: NCERT Class 10 Mathematics, Ch 6 "Triangles", §6.5_
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