If the area of an equilateral triangle is a and its height is b, then b²…

2016

If the area of an equilateral triangle is a and its height is b, then b² divided by a is

  1. A.

    1/3

  2. B.

    1/√3

  3. C.

    3

  4. D.

    √3

Show answer & explanation

Correct answer: D

For an equilateral triangle of side length s, two standard identities apply: the height is h = (√3/2)s, and the area is A = (√3/4)s². These follow from splitting the equilateral triangle into two 30-60-90 right triangles using the perpendicular from a vertex to the opposite side.

Apply these identities to this triangle, where the height is called b and the area is called a:

  1. Let the side length be s. From b = (√3/2)s, solve for s: s = 2b/√3.

  2. Square the height: b² = (3/4)s².

  3. Write the area using the standard formula: a = (√3/4)s².

  4. Divide b² by a: b²/a = (3/4)s² ÷ (√3/4)s² = 3/√3.

  5. Simplify: 3/√3 = √3.

Cross-check with a specific value: take b = 1. Then s = 2/√3, and a = (√3/4)(2/√3)² = (√3/4)(4/3) = 1/√3. So b²/a = 1 ÷ (1/√3) = √3, matching the general result.

Therefore, b²/a = √3.

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