If an equilateral triangle is inscribed in the circle x2 + y2 = a

Subject

Mathematics

Class

JEE Class 12

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 Multiple Choice QuestionsMultiple Choice Questions

11.

The small extremely fast RAM's are called as

  • cache

  • heaps

  • accumulators

  • stacks


12.

The value of i2 + i4 + i6 + ... (2n + 1) terms is

  • - 1

  • 1

  • - i

  • i


13.

The argument of the complex number  is

  • 45°

  • 60°

  • 120°

  • 150°


14.

If  be the AM of a and b, then n is equal to

  • - 1

  • 0

  • 1

  • None of these


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15.

x1/2 . x1/4 . x1/8 ...  equal to

  • 0

  • 1

  • x


16.

If the roots of the equation x2 + px + q = 0 differ by 1, then

  • p2 = 4q + 1

  • p2 = 4q

  • p2 = 4q - 1

  • p2 = - 4q


17.

If a = 2, b = 3 and c = 5in BC, then C is to equal

  • π2

  • π4

  • π6

  • None of these


18.

The centroid of the triangle formed by the lines x + y = 1, 2x + 3y = 6 and 4x - y = - 4 lies in the quadrant

  • I

  • II

  • III

  • IV


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19.

If an equilateral triangle is inscribed in the circle x2 + y2 = a2, the lenth of its each side is

  • 2a

  • 3a

  • 32a

  • 13a


B.

3a

Given equation of the circle is         x2 + y2 = a2where, radius = a

let ABC be the inscribed equnateral triangle and length of its each sides be l,

Area of ABC = 34l2Also, OD = a2 - l24     from ODB Area of OBC = 12 × l × a2 - l24Now, area of ABC = 3 × Area of OBC 34l2 = 3 × l2a2 - l24   3l = 34a2 - l2     3l2 = 94a2 - l2       l2 = 12a2 - 3l2     4l2 = 12a2       l2 = 3a2        l = 3a


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20.

If the vertex is (3,0) and the extremities of the latusrectum are (4, 3) and (4, - 3), then the equation of the parabola is

  • y2 = 4(x - 3)

  • x2 = 4(y - 3)

  • y2 = - 4(x + 3)

  • x2 = - 4(y + 3)


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