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In right triangle ABCABC above, BC=12, and AD=9. Which of the following statements, considered individually, is sufficient to determine the triangle’s area?

Area of triangle ABC = 1/2 * AB* BC, we have BC known, we need to know AB to get area of triangle ABC.

I. Triangle ABD is equilateral -> AD= AB = 9, so sufficient to get area of triangle ABC.

II. DC=6 -> AC = AD +DC = 9+6 = 15, So, we can get, AB =Sqrt (AC^2 - BC^2). Sufficient to get area of triangle ABC.

III. AB=3/4 *BC -> So, AB can be calculated. And, now, Sufficient to get area of triangle ABC.

So, I think E. :)
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Bunuel

In right triangle \(ABC\) above, \(BC = 12\), and \(AD = 9\). Which of the following statements, considered individually, is sufficient to determine the triangle’s area?

I. Triangle \(ABD\) is equilateral

II. \(DC = 6\)

III. \(AB=\frac{3}{4}BC\)

A. I only
B. II only
C. III only
D. I and II only
E. I, II, and III


imo E .

For area we need base and height . Base we know . lets evaluate for height AB .

I. Triangle \(ABD\) is equilateral so AB = AD .. sufficient .
II . \(DC = 6\) So .. AC can be found => AB can be found .. Sufficient .
III. \(AB=\frac{3}{4}BC\) => AB can be found ..

So ans is E .
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Given
    • ABC is a right-angle triangle.
    • BC=12 and AD=9

To find

    • Statement that is/are sufficient to find area of ABC.

Approach

Statement I: Triangle ABD is equilateral
    • AD = AB = 9
      o We can now find the area using ½ × BC ×AB.

Statement II: DC=6
    • We can find length of AD as AD = DC + AD
      o Then using pythagorus theorem, we can find AB and then using area formula, we can find the answer.
Statement III: AB=3/4BC
    • We already know the value of BC. So, we can find AB.
    • Then, using the area formula, we can find the area.

Hence, the correct answer is option E.
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Statement 1. If it is equilateral, then all sides will be 9, thus suffice
2: DC = 6, then we can use phyth. theorem to determine; suffice
3: AB= 3/4BC, AB= 9; suffice

Thus all suffice :)
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Triangle ABC is a right angled triangle, right angled at B. AC is the hypotenuse and hence,

\(AC^2\) = \(AB^2\) + \(BC^2\).

It is also known that BC = 12 and AD = 9.

Time to interpret the statements individually to evaluate their sufficiency to find the area of triangle ABC.

Area of triangle ABC = ½ * AB * BC = ½ * 12 * AB.
Therefore, any statement that can help us find AB is sufficient on its own.

Statement I: Triangle ABD is equilateral.

Therefore, AB = AD = 9 cm.
Statement I alone is sufficient. Answer options B and C can be eliminated.

Statement II: DC = 6

From the question, AD = 9 and also \(AC^2\) = \(BC^2\) + \(AB^2\)

From the diagram, AC = AD + DC; therefore, AC = 15. We know that BC = 12.
Substituting in the equation, AB can be calculated.
Statement II alone is sufficient. Answer option A can be eliminated.

Statement III: AB = ¾ BC.

Since BC = 12, the value of AB can be calculated.
Statement III alone is sufficient. Answer option D can be eliminated.

The correct answer option is E.
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